WorldWideScience

Sample records for aluminum garnet laser

  1. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    Science.gov (United States)

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  2. Determinants of holmium:yttrium-aluminum-garnet laser time and energy during ureteroscopic laser lithotripsy.

    Science.gov (United States)

    Molina, Wilson R; Marchini, Giovanni S; Pompeo, Alexandre; Sehrt, David; Kim, Fernando J; Monga, Manoj

    2014-04-01

    To evaluate the association of preoperative noncontrast computed tomography stone characteristics, laser settings, and stone composition with cumulative holmium:yttrium-aluminum-garnet (Ho:YAG) laser time/energy. We retrospectively reviewed patients who underwent semirigid/flexible ureteroscopy and Ho:YAG laser lithotripsy (200 or 365 μm laser fiber; 0.8-1.0 J energy; and 8-10 Hz rate) at 2 tertiary care centers (April 2010-May 2012). Studied parameters were as follows: patient's characteristics; stone characteristics (location, burden, hardness, and composition); total laser time and energy; and surgical outcomes. One hundred patients met our inclusion criteria. Mean stone size was 1.01 ± 0.42 cm and volume 0.33 ± 0.04 cm(3). Mean stone radiodensity was 990 ± 296 HU, and Hounsfield units density 13.8 ± 6.0 HU/mm. All patients were considered stone free. Stone size and volume had a significant positive correlation with laser energy (R = 0.516, P R = 0.621, P R = 0.477, P R = 0.567, P stone size, only the correlation between HU and laser time was significant (R = 0.262, P = .011). In the multivariate analysis, with exception of stone composition (P = .103), all parameters significantly increased laser energy (R(2) = 0.524). Multivariate analysis revealed a positive significant association of laser time with stone volume (P R(2) = 0.512). In multivariate analysis for laser energy, only calcium phosphate stones required less energy to fragment compared with uric acid stones. No significant differences were found in the multivariate laser time model. Ho:YAG laser cumulative energy and total time are significantly affected by stone dimensions, hardness location, fiber size, and power. Kidney location, laser fiber size, and laser power have more influence on the final laser energy than on the total laser time. Calcium phosphate stones require less laser energy to fragment. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Microtensile bond strength of composite resin to human enamel prepared using erbium: Yttrium aluminum garnet laser.

    Science.gov (United States)

    Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Palma-Dibb, Regina Guenka

    2007-02-01

    The Erbium: Yttrium Aluminum Garnet (YAG) laser used for preparation of cavity can alter the substrate and it could influence the bond strength of enamel. The aim of this in vitro study was to evaluate the influence of Er:YAG laser's energy using microtensile bond test. Three groups were obtained (cavity preparation) and each group was divided into two subgroups (adhesive system). After that the adhesive protocol was performed, sections with a cross-sectional area of 0.8 mm2 (+/-0.2 mm2) were obtained. The specimens were mounted in a universal testing machine (0.5 mm/min). Statistical analysis showed a decrease in bond strength for lased groups (p adhesive system was used the laser 300 mJ subgroup showed higher bond strength compared to the laser 250 mJ (p adhesive procedures than conventional bur-cut cavities. Copyright 2006 Wiley Periodicals, Inc.

  4. Fractional versus ablative erbium:yttrium-aluminum-garnet laser resurfacing for facial rejuvenation: an objective evaluation.

    Science.gov (United States)

    El-Domyati, Moetaz; Abd-El-Raheem, Talal; Abdel-Wahab, Hossam; Medhat, Walid; Hosam, Wael; El-Fakahany, Hasan; Al Anwer, Mustafa

    2013-01-01

    Laser is one of the main tools for skin resurfacing. Erbium:yttrium-aluminum-garnet (Er:YAG) was the second ablative laser, after carbon dioxide, emitting wavelength of 2940 nm. Fractional laser resurfacing has been developed to overcome the drawbacks of ablative lasers. We aimed to objectively evaluate the histopathological and immunohistochemical effects of Er:YAG 2940-nm laser for facial rejuvenation (multiple sessions of fractional vs single session of ablative Er:YAG laser). Facial resurfacing with single-session ablative Er:YAG laser was performed on 6 volunteers. Another 6 were resurfaced using fractional Er:YAG laser (4 sessions). Histopathological (hematoxylin-eosin, orcein, Masson trichrome, and picrosirius red stains) and immunohistochemical assessment for skin biopsy specimens were done before laser resurfacing and after 1 and 6 months. Histometry for epidermal thickness and quantitative assessment for neocollagen formation; collagen I, III, and VII; elastin; and tropoelastin were done for all skin biopsy specimens. Both lasers resulted in increased epidermal thickness. Dermal collagen showed increased neocollagen formation with increased concentration of collagen types I, III, and VII. Dermal elastic tissue studies revealed decreased elastin whereas tropoelastin concentration increased after laser resurfacing. Neither laser showed significant difference between their effects clinically and on dermal collagen. Changes in epidermal thickness, elastin, and tropoelastin were significantly more marked after ablative laser. The small number of patients is a limitation, yet the results show significant improvement. Multiple sessions of fractional laser have comparable effects to a single session of ablative Er:YAG laser on dermal collagen but ablative laser has more effect on elastic tissue and epidermis. Copyright © 2012 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  5. Erbium-yttrium-aluminum-garnet laser irradiation ameliorates skin permeation and follicular delivery of antialopecia drugs.

    Science.gov (United States)

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Aljuffali, Ibrahim A; Li, Yi-Ching; Fang, Jia-You

    2014-11-01

    Alopecia usually cannot be cured because of the available drug therapy being unsatisfactory. To improve the efficiency of treatment, erbium-yttrium-aluminum-garnet (Er-YAG) laser treatment was conducted to facilitate skin permeation of antialopecia drugs such as minoxidil (MXD), diphencyprone (DPCP), and peptide. In vitro and in vivo percutaneous absorption experiments were carried out by using nude mouse skin and porcine skin as permeation barriers. Fluorescence and confocal microscopies were used to visualize distribution of permeants within the skin. Laser ablation at a depth of 6 and 10 μm enhanced MXD skin accumulation twofold to ninefold depending on the skin barriers selected. DPCP absorption showed less enhancement by laser irradiation as compared with MXD. An ablation depth of 10 μm could increase the peptide flux from zero to 4.99 and 0.33 μg cm(-2) h(-1) for nude mouse skin and porcine skin, respectively. The laser treatment also promoted drug uptake in the hair follicles, with DPCP demonstrating the greatest enhancement (sixfold compared with the control). The imaging of skin examined by microscopies provided evidence of follicular and intercellular delivery assisted by the Er-YAG laser. Besides the ablative effect of removing the stratum corneum, the laser may interact with sebum to break up the barrier function, increasing the skin delivery of antialopecia drugs. The minimally invasive, well-controlled approach of laser-mediated drug permeation offers a potential way to treat alopecia. This study's findings provide the basis for the first report on laser-assisted delivery of antialopecia drugs. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  6. Neodymium:Yttrium aluminum garnet laser in the management of oral leukoplakia: A case series

    Directory of Open Access Journals (Sweden)

    Somdipto Das

    2015-01-01

    Full Text Available Objectives: Oral leukoplakia is a nonscrappable whitish patch described as a potentially malignant disorder with high prevalence in India. Besides medicinal treatment, neodymium: Yttrium aluminum garnet (Nd: YAG laser is also used for the management of oral leukoplakia. This study evaluated the role of Nd: YAG laser in the management of oral leukoplakia and also investigated postoperative complications along with long-term prognosis of the disease. Settings and Designs: The study is a prospective cohort study conducted for 24 months (June 2011 to May 2013 in Lucknow. Materials and Methods: The study comprised of 42 patients, both male and female of Indian origin and diagnosed with oral leukoplakic lesions. Patients with biopsy proven squamous cell carcinoma and medically compromised are excluded from the study. All patients has undergone ablation of lesion by pulsed Nd: YAG laser and were followed after 24 h, 72 h, 1-week and then successively for 1, 3, 6 months and then 1 st and 2 nd postoperative years. Results: Pain and slough were evaluated by Wicoxon rank test (P = 0.0001 statistically significant which decreased from 24 h to 1-week and became nil in subsequent follow-ups. Similarly, McNemar′s test (P = 0.001 statistically significant was used for evaluation of burning sensation, paresthesia, infection and recurrences. Recurrence was noted in 2 patients but following the second application, there were no recurrences over the period of further follow-up. None of the patient suffered from an infection, paresthesia or anesthesia. Conclusion: Hence, Nd: YAG laser was found to be effective in ablating leukoplakia. It is convenient, economical with minimum complications and morbidities.

  7. Endothelial cell study in a case of Werner′s syndrome undergoing phacoemulsification and Yettrium-Aluminum-Garnet laser capsulotomy

    Directory of Open Access Journals (Sweden)

    Vasudha Kemmanu

    2012-01-01

    Full Text Available Werner′s syndrome (WS is a rare autosomal recessive disorder with multisystem manifestations of premature aging from the second decade of life. Cataract is one of the features of WS. Cataract surgery is complicated with postoperative wound dehiscence and bullous keratopathy when the surgery is done by intracapsular or conventional extracapsular method. We report the short-term result of phacoemulsification and Neodymimum Yettrium-Aluminum-Garnet laser (Nd YAG capsulotomy in a case of WS with bilateral cataracts. Postoperatively and post capsulotomy, there was no change in the endothelial cell morphology. There was an 8.6% decrease in endothelial cell count at the end of 15 months postoperatively and 11 months post YAG capsulotomy. This decrease is within the acceptable range of cell loss after phacoemulsification and YAG capsulotomy. To the best of our knowledge, this is the first reported case of YAG laser capsulotomy in WS.

  8. Dynamics of laser-induced magnetization in Ce-doped yttrium aluminum garnet

    International Nuclear Information System (INIS)

    Kolesov, Roman

    2007-01-01

    Circularly polarized short laser pulse induces nonequilibrium population of spin levels in the excited state of Ce 3+ -ion embedded in yttrium aluminium garnet crystal and, consequently, the magnetization of the crystal associated with spin polarization. Dynamic behavior of laser-induced magnetization is studied as a function of the external magnetic field. It reveals spin oscillations attributed to the effect of hyperfine magnetic field produced by 27 Al nuclei on the Ce 3+ spin. A simple theoretical model explaining spin oscillations is presented. It shows that circularly polarized light induces spin coherence at the transition between Zeeman sublevels of Ce 3+ ion in the lowest 5d state. Temporal shape of laser-induced magnetization signal reveals the following parameters of this state: (1) the spin-lattice relaxation constant is ≅2x10 7 s -1 , (2) inhomogeneous spin dephasing time is ≅4 ns, and (3) the g tensor of the state seems to be isotropic with the g factor being in the range 0.7-0.9. In addition, the width of the local hyperfine field distribution is ≅40 G

  9. Fractional erbium-doped yttrium aluminum garnet laser-assisted drug delivery of hydroquinone in the treatment of melasma

    Science.gov (United States)

    Badawi, Ashraf M; Osman, Mai Abdelraouf

    2018-01-01

    Background Melasma is a difficult-to-treat hyperpigmentary disorder. Ablative fractional laser (AFL)-assisted delivery of topically applied drugs to varied targets in the skin has been an area of ongoing study and research. Objective The objective of this study was to evaluate the efficacy and safety of fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser as an assisted drug delivery for enhancing topical hydroquinone (HQ) permeation into the skin of melasma patients. Patients and methods Thirty female patients with bilateral melasma were randomly treated in a split-face controlled manner with a fractional Er:YAG laser followed by 4% HQ cream on one side and 4% HQ cream alone on the other side. All patients received six laser sessions with a 2-week interval. The efficacy of treatments was determined through photographs, dermoscopic photomicrographs and Melasma Area Severity Index (MASI) score, all performed at baseline and at 12 weeks of starting therapy. The patient’s level of satisfaction was also recorded. Results Er:YAG laser + HQ showed significantly better results (plaser + HQ side vs HQ side. Minor reversible side effects were observed on both sides. Conclusion AFL-assisted delivery of HQ is a safe and effective method for the treatment of melasma. PMID:29379308

  10. Does ErbiumiYttrium-Aluminum-Garnet Laser to Enamel improve the Performance of Etch-and-rinse and Universal Adhesives?

    Science.gov (United States)

    De Jesus Tavarez, Rudys R; Rodrigues, Lorrany Lc; Diniz, Ana C; Lage, Lucas M; Torres, Carlos Rg; Bandeca, Matheus C; Firoozmand, Leily M

    2018-03-01

    This study aims to evaluate the effect of erbium: Yttrium-aluminum-garnet (Er:YAG) laser irradiation on the enamel microshear bond strength (μSBS), followed by the utilization of etch-and-rinse and universal adhesive systems. A total of 32 molars were sectioned in the mesiodistal direction producing 64 samples that were randomized into two groups (n = 32): single bond 2 (SB2) (etch-and-rinse system; 3M), SB universal (SBU) (universal etching system; The SB2 and SBU groups were then divided into two subgroups (n = 16): (i) enamel was irradiated with an Er:YAG laser (λ = 2.94 μm, 60 mJ, 10 Hz), and (ii) enamel served as a control. The samples were restored with TPH3 (Dentsply), stored in artificial saliva for 24 hours, and subjected to a micro-shear test. Kruskal-Wallis (p enamel interface. The previous irradiation of enamel with Er:YAG laser does not interfere with the performance of simplified two-step etch-and-rinse and universal adhesive systems. The increasing use of Er:YAG laser is important to evaluate the influence of this irradiation on the adhesion of restorative materials. Thus, to obtain the longevity of the restorative procedures, it is necessary to know the result of the association of the present adhesive systems to the irradiated substrate.

  11. Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2014-01-01

    Full Text Available Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under Χ10 magnification and adhesive remnant index (ARI score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa (P = 0.41. There was no significant difference in the ARI scores between two groups (P = 0.08. However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching.

  12. The Effect of Neodymium: Yttrium Aluminum Garnet and Fractional Carbon Dioxide Lasers on Alopecia Areata: A Prospective Controlled Clinical Trial.

    Science.gov (United States)

    Yalici-Armagan, Basak; Elcin, Gonca

    2016-04-01

    Effective treatment options for alopecia areata (AA) are missing. Whether lasers might be effective is a topic of debate. We aimed to evaluate whether neodymium: yttrium aluminum garnet (Nd:YAG) or fractional carbon dioxide lasers might stimulate the development of new hair. Thirty-two patients who had long-standing and treatment refractory diseases were recruited for the study. Three different patches on the scalp were selected, 1 of which served as control. The mean outcome measure was the hair count, which was calculated with the digital phototrichogram. Response was defined as at least 25% increase in the mean hair count at the treated patch compared with the control patch. At the end of the study, there was no statistically significant difference in the mean hair count for the 3 patches. In 7 of 32 patients (22%), an increase in the mean hair count was observed on the whole scalp including the control patch, which resulted in an improved Severity of Alopecia Tool (SALT) score. We have observed that Nd:YAG or fractional carbon dioxide lasers did not increase the mean hair count on the treated AA patches when compared with the control patch. However, an SALT score improvement in 22% of the patients suggested spontaneous remission.

  13. Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

    Science.gov (United States)

    Puri, Neerja

    2015-01-01

    Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

  14. Yttrium aluminum garnet coating on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J., E-mail: eduardo.nassar@unifran.edu.br

    2016-02-15

    Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu{sup 3+} onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min{sup −1} and evaporation led to deposition of different numbers of layers of the YAG:Eu{sup 3+} film onto the glass substrate from a YAG:Eu{sup 3+} powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu{sup 3+}. • The matrix was deposited as transparent films. • The YAG:Eu{sup 3+} was deposited by sol–gel process onto glass substrate.

  15. Yttrium aluminum garnet coating on glass substrate

    International Nuclear Information System (INIS)

    Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J.

    2016-01-01

    Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu 3+ onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min −1 and evaporation led to deposition of different numbers of layers of the YAG:Eu 3+ film onto the glass substrate from a YAG:Eu 3+ powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu 3+ . • The matrix was deposited as transparent films. • The YAG:Eu 3+ was deposited by sol–gel process onto glass substrate.

  16. Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

    Science.gov (United States)

    Maeda, Y

    1994-08-10

    An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

  17. Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

    Science.gov (United States)

    Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

    2017-10-01

    This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd

  18. Microstructured silicon created with a nanosecond neodymium-doped yttrium aluminum garnet laser

    Energy Technology Data Exchange (ETDEWEB)

    Mandeville, W.J. [MITRE Corporation, Colorado Springs, CO (United States); Shaffer, M.K.; Lu, Yalin; O' Keefe, D.; Knize, R.J. [United States Air Force Academy, USAFA, CO (United States)

    2011-08-15

    We produce microstructured silicon using frequency doubled, nanosecond Nd:YAG pulses in SF{sub 6} gas. The micro-penitentes formed are up to 20 {mu}m tall with a sulfur concentration of 0.5% near the surface. The infrared absorption is increased to near unity and extends well below the original bandgap far into the infrared. These data are similar to results reported by others using more complicated and less economical femtosecond titanium sapphire and picosecond and nanosecond excimer lasers. (orig.)

  19. A comparative scanning electron microscopy study between hand instrument, ultrasonic scaling and erbium doped:Yttirum aluminum garnet laser on root surface: A morphological and thermal analysis

    Directory of Open Access Journals (Sweden)

    Mitul Kumar Mishra

    2013-01-01

    Full Text Available Background and Objectives: Scaling and root planing is one of the most commonly used procedures for the treatment of periodontal diseases. Removal of calculus using conventional hand instruments is incomplete and rather time consuming. In search of more efficient and less difficult instrumentation, investigators have proposed lasers as an alternative or as adjuncts to scaling and root planing. Hence, the purpose of the present study was to evaluate the effectiveness of erbium doped: Yttirum aluminum garnet (Er:YAG laser scaling and root planing alone or as an adjunct to hand and ultrasonic instrumentation. Subjects and Methods: A total of 75 freshly extracted periodontally involved single rooted teeth were collected. Teeth were randomly divided into five treatment groups having 15 teeth each: Hand scaling only, ultrasonic scaling only, Er:YAG laser scaling only, hand scaling + Er:YAG laser scaling and ultrasonic scaling + Er:YAG laser scaling. Specimens were subjected to scanning electron microscopy and photographs were evaluated by three examiners who were blinded to the study. Parameters included were remaining calculus index, loss of tooth substance index, roughness loss of tooth substance index, presence or absence of smear layer, thermal damage and any other morphological damage. Results: Er:YAG laser treated specimens showed similar effectiveness in calculus removal to the other test groups whereas tooth substance loss and tooth surface roughness was more on comparison with other groups. Ultrasonic treated specimens showed better results as compared to other groups with different parameters. However, smear layer presence was seen more with hand and ultrasonic groups. Very few laser treated specimens showed thermal damage and morphological change. Interpretation and Conclusion: In our study, ultrasonic scaling specimen have shown root surface clean and practically unaltered. On the other hand, hand instrument have produced a plane surface

  20. The effectiveness of long-pulse 1064 nm neoymium-doped yttrium aluminum garnet laser for recalcitrant palmoplantar and ungual warts

    Directory of Open Access Journals (Sweden)

    Ali Balevi

    2015-12-01

    Full Text Available Background and Design: Some of palmoplantar and ungual warts are resistant to conventional treatments. In this study, we aimed to investigate the efficacy of non-ablative 1064 nm long pulsed neoymium-doped yttrium aluminum garnet (Nd: YAG laser treatment on recalcitrant palmoplantar and ungual warts. Materials and Methods: Sixty-three patients with recalcitrant palmar, plantar and ungual warts were included in the study. Laser is applied in 4 sessions at 4-week intervals. The study employed the Nd: YAG (80 W. The following parameters were used: spot size: 4 mm; pulse duration: 15 msec; and fluence: 150 J/cm2. Treatment responses were evaluated statistically and side effects were recorded. Results: The number of patients who were completely cleaned and partially cleaned were 37 (66% and 15 (26%, respectively. Four patients (4% did not respond to treatment. In statistical analysis, there were no significant differences in palmar, plantar or ungual sites in term of complete clearance (p=0.20, p=0.82 and p=0.94, respectively. In addition, there was no association between the number of lesions and complete clearance (p=0.97. Conclusion: Long-pulsed Nd: YAG laser, which does not affect daily activity, is a safe and alternative method and may be recommended for patients with recalcitrant palmoplantar and ungual warts.

  1. Comparison of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet laser for treatment of cosmetic tattoos containing titanium and iron in an animal model.

    Science.gov (United States)

    Wang, Chia-Chen; Huang, Chuen-Lin; Yang, An-Hang; Chen, Chih-Kang; Lee, Shao-Chen; Leu, Fur-Jiang

    2010-11-01

    Cosmetic tattoos contain titanium and ferric oxide and darken through reduction after Q-switched laser irradiation. The optimal treatment for removing these pigments remains unknown. To compare the effects of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet (SP Er:YAG) laser to remove cosmetic tattoos in an animal model. Rats were tattooed using white, flesh-colored, and brown inks (4 bands of each color) on their backs. For each color, one band was left untreated, and one each was treated with a Q-switched neodymium-doped YAG laser, a Q-switched alexandrite laser, and a SP Er:YAG laser every 3 weeks until the pigments were clear. The two Q-switched lasers were equally effective; all three pigments darkened initially and then resolved gradually. Up to 20, 18, and 10 sessions were required to remove white, flesh-colored, and brown tattoos, respectively. Only six sessions were required with the SP Er:YAG laser. Minimal scarring was observed with all lasers. Skin biopsies confirmed pigment granule fragmentation after Q-switched laser treatment and a decrease in the amount of pigment after SP Er:YAG laser treatment. The SP Er:YAG laser was superior to the Q-switched lasers for removing cosmetic tattoos. © 2010 by the American Society for Dermatologic Surgery, Inc.

  2. Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos.

    Science.gov (United States)

    Lakshmi, Chembolli; Krishnaswamy, Gayathri

    2015-01-01

    Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm(2). The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals.

  3. Correlation of performance with endoscopic and radiographic assessment of epiglottic hypoplasia in racehorses with epiglottic entrapment corrected by use of contact neodymium:yttrium aluminum garnet laser

    International Nuclear Information System (INIS)

    Tulleners, E.P.

    1991-01-01

    Epiglottic entrapment in 35 Thoroughbred and 44 Standardbred horses was corrected transendoscopically by use of a neodymium:yttrium aluminum garnet laser. Before surgery, the entrapped epiglottis was classified as hypoplastic or normal in each horse on the basis of endoscopic appearance alone. Using a digitizer, thyroepiglottic length was determined from lateral-view laryngeal radiographs. For 78 racehorses, earnings (less than $5,000 or greater than $5,000) were compared before and after surgery. Earnings category and racing performance after surgery were tested for association with endoscopically determined epiglottic hypoplasia and radiographically determined thyroepiglottic length. Endoscopy and radiography were useful methods of evaluating the epiglottis in horses with epiglottic entrapment. Mean (+/- SD) thyroepiglottic length for both breeds of horses with epiglottic entrapment was significantly (P = 0.0001) smaller (Thoroughbreds, 7.28 +/- 0.67 cm; Standardbreds, 7.21 +/- 0.62 cm), compared with thyroepiglottic length measured from control groups composed of clinically normal Thoroughbred (8.56 +/- 0.29 cm) and Standardbred (8.74 +/- 0.38 cm) racehorses. Both breeds of horses with epiglottic entrapment that had endoscopically apparent hypoplastic epiglottis had significantly (P less than 0.0001) smaller thyroepiglottic length (Thoroughbreds, 6.64 +/- 0.60 cm; Standardbred, 6.93 +/- 0.72 cm) than did horses with epiglottic entrapment that had endoscopically normal epiglottis (Throughbreds, 7.57 +/- 0.47 cm, Standardbreds, 7.36 +/- 0.50 cm). Significant difference was not detected in endoscopic appearance of the epiglottis among age, gender, or breed distributions

  4. Starting mechanisms and dynamics of bubble formation induced by a Ho:Yttrium aluminum garnet laser in water

    Science.gov (United States)

    Frenz, Martin; Könz, Flurin; Pratisto, Hans; Weber, Heinz P.; Silenok, Alexander S.; Konov, Vitaly I.

    1998-12-01

    The starting mechanisms and dynamics of laser-induced bubble formation at a submerged fiber tip in distilled water were experimentally investigated using pressure measurements and fast flash videography. A fiber guided Ho:YAG laser operating in the free running (τ=200 μs) and Q-switched (τ=45 ns) mode at a wavelength of λ=2.12 μm was used as a light source. It is shown that the beam profile at the distal fiber tip (multimode fiber d=300 μm) exhibits hot spots that result in an inhomogeneous temperature distribution in the heated water volume. Depending on the laser irradiance, three different bubble formation processes are distinguished: bubble formation by heating, by rarefraction (cavitation), and by a combination of these two processes. For laser irradiances of less than 0.5 MW/ cm2 bubble formation takes place at temperatures near the critical point of water (T=280 °C). A rapid decrease in the threshold temperature for bubble formation was found for laser irradiances between 0.5 and 1 MW/cm 2. At laser irradiances higher than 3 MW/cm2, microbubbles with radii of up to 20 μm were formed at the front of the laser pulse even though the average water temperature was far below 100 °C. The water temperature distribution during the laser pulse was determined by numerical simulation. Simultaneous pressure measurements revealed that each subablative laser spike induces a bipolar pressure transient. The onset of the bubble expansion was found to be correlated with a characteristic pressure increase that can be used for on-line monitoring of the ablation process. The distortion of the temporal profile of the pressure wave is shown to be an effect of diffraction. The reduction of pressure by the negative part of the bipolar pressure transients leads to a lowering of the evaporation pressure and therefore to the initiation of bubbles by cavitation. With increasing irradiance this mechanism becomes more efficient.

  5. Macro-structural effect of metal surfaces treated using computer-assisted yttrium-aluminum-garnet laser scanning on bone-implant fixation.

    Science.gov (United States)

    Hirao, Makoto; Sugamoto, Kazuomi; Tamai, Noriyuki; Oka, Kunihiro; Yoshikawa, Hideki; Mori, Yusuke; Sasaki, Takatomo

    2005-05-01

    Porous coatings have been applied to the surface of prosthetic devices to foster stable device fixation. The coating serves as a source of mechanical interlocking and may stimulate healthy bone growth through osseointegrated load transfer in cementless arthroplasty. Joint arthroplasty by porous-coated prostheses is one of the most common surgical treatments, and has provided painless and successful joint mobility. However, long-term success is often impaired by the loss of fixation between the prosthesis and bone. Porous-coated prostheses are associated with several disadvantages, including metal debris from porous coatings (third body wear particles) and irregular micro-texture of metal surfaces. Consequently, quantitative histological analysis has been very difficult. These issues arise because the porous coating treatment is based on addition of material and is not precisely controllable. We recently developed a precisely controllable porous texture technique based on material removal by yttrium-aluminum-garnet laser. Free shapes can be applied to complex, three-dimensional hard metal surfaces using this technique. In this study, tartan check shapes made by crossing grooves and dot shapes made by forming holes were produced on titanium (Ti6A14V) or cobalt chrome (CoCr) and evaluated with computer-assisted histological analysis and measurement of bone-metal interface shear strength. Width of grooves or holes ranged from 100 to 800 mum (100, 200, 500, and 800 microm), with a depth of 500 microm. When the cylindrical porous-texture-treated metal samples (diameter, 5 mm; height, 15 mm) were implanted into a rabbit femoral condyle, bone tissue with bone trabeculae formed in the grooves and holes after 2 or 4 weeks, especially in 500-microm-wide grooves. Abundant osteoconduction was consistently observed throughout 500-microm-wide grooves in both Ti6A14V and CoCr. Speed of osteoconduction was faster in Ti6A14V than in CoCr, especially in the tartan check shape made of

  6. Structure-terahertz property relationship in yttrium aluminum garnet ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Steere, D.W.; Clark, B.M.; Sundaram, S.K. [Alfred University, Terahertz and Millimeter Waves Laboratory (T-Lab), Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred, NY (United States); Gaume, R. [Townes Laser Institute and the NanoScience Technology Center, CREOL, The College of Optics and Photonics, Orlando, FL (United States)

    2017-08-15

    Terahertz (THz) transmission measurements on chemically variant yttrium aluminum garnet (YAG) ceramics are described. Chemical compositions and processing parameters were varied to determine the effect of stoichiometry, density, and pore volume distribution on the optical and dielectric properties in the THz frequency regime. Density has the largest effect on properties out of the parameters that were investigated. In addition, a linear correlation between cubic root of real permittivity at 1 THz and average density of these samples is observed. Our results show promise for design and fabrication of advanced optical materials and devices with desired THz properties via controlling density and porosity of the materials. (orig.)

  7. Picosecond 532-nm neodymium-doped yttrium aluminum garnet laser-a promising modality for the management of verrucous epidermal nevi.

    Science.gov (United States)

    Levi, Assi; Amitai, Dan Ben; Mimouni, Daniel; Leshem, Yael A; Arzi, Ofir; Lapidoth, Moshe

    2018-04-01

    The verrucous epidermal nevus (VEN) is the most common type of epidermal nevi. As lesions can be disfiguring, treatment is often sought. Many therapeutic approaches have been reported, with variable efficacy and safety. Picosecond (PS) lasers are novel laser devices designated to target small chromophores. A side effect of these lasers is blistering due to epidermal-dermal separation. We aimed to harness this side effect of the PS lasers to treat patients with VEN. The purpose of this study was to report our experience treating VEN using a PS 532-nm laser. We present a retrospective case series of six patients with large VEN who were treated using a PS 532-nm laser (2-6 treatments, 8-10 weeks apart). Response in clinical photographs was assessed by two independent dermatologists and graded on a scale of 0 (exacerbation) to 4 (76-100% improvement). Patient satisfaction was recorded on a scale of 1-5. All patients demonstrated significant improvement. Average improvement was 3.7 on the quartile scale of improvement. Patient satisfaction rate averaged 4.7. The PS 532-nm laser is a promising novel modality for the treatment of large VEN.

  8. Efficiency of ablative fractional Er: YAG (Erbium: Yttrium-Aluminum-Garnet laser treatment of epidermal and dermal benign skin lesions: A retrospective study

    Directory of Open Access Journals (Sweden)

    Erol Koç

    2014-03-01

    Full Text Available Background: Er: YAG lasers are precise ablation systems used in the treatment epidermal and dermal benign skin lesions. In this study, we restrospectively analysed efficiency of Er: YAG laser therapy in the treatment of epidermal and dermal benign skin lesions. Materials and Methods: We retrospectively investigated our clinical records of 116 patients treated with Er: YAG laser between April 2011 and April 2013. The clinical records of 103 patients (47 men, 56 women were included in our study. Of these 103 patients included in the study were xanthelasma, solar lentigo, epidermal nevus, seborrheic keratosis, nevus of ota, syringoma, cafe au lait macules (CALM and other than these. Treatment parameters, demographic features and before and after photographs of the lesions were investigated from patients’ records in order to evaluate efficiency of Er: YAG laser therapy. Results: Of these 103 patients included in the study were evaluated in 8 groups, described as xanthelasma (n=21, syringoma (n=17, solar lentigo (n=16, epidermal nevus (n=11, seborrheic keratosis (n=9, nevus of ota (n=5, CALM (n=3 and other than these (n=21. In the Er: YAG laser treatment, the average energy flow was 3-7 J/cm2, the average pulse duration was 300 ms, the average number of passes was 3-5 repeat, and the average pulse frequency was 3-7 Hz. While 4.9% of the patients showed no improvement, 59.2% showed marked improvement, 26.2% showed moderate improvement and 9.7% showed mild improvement. Treatment responses in xanthelasma, syringoma, epidermal nevus, solar lentigo and CALM lesions were statistically significant. Observed side effects were hyperpigmentation in 4 patients, hypopigmentation in 3 patients, hypertrophic scar in 2 patients and persistent erythema in one patient and the treatment was well tolerated by all the patients. Conclusion: Er: YAG laser is an effective and safe treatment option in the treatment of benign skin lesions especially in epidermal lesions.

  9. Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

    Science.gov (United States)

    Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

    2018-02-01

    Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

  10. Preliminary panoramic study of river calm muscle using neodymium:yttrium-aluminum-garnet (Nd: YAG) laser-induced breakdown spectroscopy (LIBS)

    Science.gov (United States)

    Idris, N.; Lahna, K.; Usmawanda, T. N.; Herman; Ramli, M.; Hedwig, R.; Marpaung, A. M.; Kurniawan, K. H.

    2018-04-01

    A wide coverage spectral investigation on the muscle of river calm sample has been carried out using laser-induced breakdown spectroscopy for examining the overall profile of the emission spectra from the produced plasma. The basic apparatus of LIBS system used is a Nd-YAG laser and wide coverage optical multichannel analyzer (OMA) system. The river clam samples used is collected from Panga River in Aceh Jaya Regency, Aceh, Indonesia up streaming in a mountain of Gunong Ujeun, which is used as a location of the intensive traditional mining activity. Assuming that heavy metal accumulated in the clam muscle, LIBS experiments were carried out on the muscle of the calm. The sample used was fresh muscle sliced and attached to a copper plate. Plasma was generated by focusing the laser beam on the sample surface under air surrounding gas at 1 atmosphere. It is found that there are only major elements of host organic, namely C, H, O, N and the minor element of salts can be detected from fresh the clam sample when using a high pulse laser energy under air surrounding at high pressure of 1 atmosphere. There is no emission lines from any metal can be detected. Several experimental parameters were explored to study the panoramic dynamic of the emission spectra. It is found that the lower energy and the lower pressure is better for obtaining better emission spectra showing the possibility for determination of the analyte.

  11. Comparative study of the influence of the gas injection system on the Nd:yttrium-aluminum-garnet laser cutting of advanced oxide ceramics

    International Nuclear Information System (INIS)

    Quintero, F.; Pou, J.; Lusquinos, F.; Boutinguiza, M.; Soto, R.; Perez-Amor, M.

    2003-01-01

    Cutting of advanced oxide ceramics is still a difficult task. In this work, the possibility to effectively cut them using a Nd:YAG laser guided by an optical fiber is demonstrated. The key points are the aerodynamic interactions of the assist gas jet in the fusion laser cutting of ceramics. A comprehensive study of the influence of these aerodynamic interactions on the laser cutting of advanced oxide ceramics has been carried out. The characteristics of the heat affected zone (HAZ) were studied related to the efficiency of the assist gas to eject the molten material. It has been demonstrated that the HAZ can be avoided with a suitable design of the gas injection system combined with an appropriate selection of the values of the processing parameters. With the aim of improving the efficiency of the assist gas injection system, a new cutting head with an off-axis supersonic nozzle was developed. Furthermore, a comparison between the utilization of a conventional coaxial conical nozzle to inject the assist gas and the new system is presented. The results obtained give clear proof that the use of the new gas injection system leads to a great improvement on the cut quality by means of a more efficient removing of the molten material out of the cutting front. This result is of special interest in the laser fusion cutting of thick ceramic plates at high processing rates

  12. Split-face comparison of long-pulse-duration neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser alone and combination long-pulse and Q-switched Nd:YAG 1,064-nm laser with carbon photoenhancer lotion for the treatment of enlarged pores in Asian women.

    Science.gov (United States)

    Wattanakrai, Penpun; Rojhirunsakool, Salinee; Pootongkam, Suwimon

    2010-11-01

    Long-pulse and Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser used for facial rejuvenation can improve pore size. Topical carbon has been used to enhance efficacy. To compare the efficacy and safety of a 1,064-nm long-pulse Nd:YAG laser alone with that of a combination Q-switched Nd:YAG laser with topical carbon lotion followed by long-pulse Nd:YAG to improve enlarged pores. Twenty Thai women randomly received five treatments with a long-pulse Nd:YAG laser on one facial half (LP side) and long-pulse Nd:YAG after carbon-assisted Q-switched Nd:YAG laser on the contralateral side (carbon QS+LP side) at 2-week intervals. Participants were evaluated using digital photography, complexion analysis, and a chromometer. There was significant decrease in pore counts of 35.5% and 33% from baseline on the carbon QS+LP and LP sides, respectively. Physician-evaluated pore size improvement was 67% on the carbon QS+LP sides and 60% on the LP sides. Chromometer measurement showed an increase in skin lightness index. There was no significant difference between the two treatments, although there were more adverse effects on the carbon QS+LP side. Long-pulse Nd:YAG 1,064-nm laser improves the appearance of facial pores and skin color. Adding carbon-assisted Q-switched Nd:YAG did not enhance the results but produced more side effects. © 2010 by the American Society for Dermatologic Surgery, Inc.

  13. Aluminum and gallium nuclei as microscopic probes for pulsed electron-nuclear double resonance diagnostics of electric-field gradient and spin density in garnet ceramics doped with paramagnetic ions

    Science.gov (United States)

    Uspenskaya, Yu. A.; Mamin, G. V.; Babunts, R. A.; Badalyan, A. G.; Edinach, E. V.; Asatryan, H. R.; Romanov, N. G.; Orlinskii, S. B.; Khanin, V. M.; Wieczorek, H.; Ronda, C.; Baranov, P. G.

    2018-03-01

    The presence of aluminum and gallium isotopes with large nuclear magnetic and quadrupole moments in the nearest environment of impurity ions Mn2+ and Ce3+ in garnets made it possible to use hyperfine and quadrupole interactions with these ions to determine the spatial distribution of the unpaired electron and the gradient of the electric field at the sites of aluminum and gallium in the garnet lattice. High-frequency (94 GHz) electron spin echo detected electron paramagnetic resonance and electron-nuclear double resonance measurements have been performed. Large difference in the electric field gradient and quadrupole splitting at octahedral and tetrahedral sites allowed identifying the positions of aluminum and gallium ions in the garnet lattice and proving that gallium first fills tetrahedral positions in mixed aluminum-gallium garnets. This should be taken into account in the development of garnet-based scintillators and lasers. It is shown that the electric field gradient at aluminum nuclei near Mn2+ possessing an excess negative charge in the garnet lattice is ca. 2.5 times larger than on aluminum nuclei near Ce3+.

  14. Cathodoluminescence properties of yttrium aluminum garnet doped with Eu2+ and Eu3+ ions

    International Nuclear Information System (INIS)

    Trofimov, A. N.; Petrova, M. A.; Zamoryanskaya, M. V.

    2007-01-01

    Yttrium aluminium garnet (YAG) doped with Eu 2+ and Eu 3+ ions is very interesting as a phosphor for conversion of light-emitting diode light for white light sources. The europium ion occupies the structural position of yttrium in yttrium aluminium garnet and has valence state Eu 3+ . Our sample was doped with Zr 4+ , which is why some of the europium ions had valence state Eu 2+ . As a rule, luminescence of Eu 3+ ions is observed in the orange and red range of spectrum. The luminescence of Eu 2+ in yttrium aluminum garnet is characterized by an intensive broad band with maximum of intensity at about 560 nm (green color). In this work, we studied the intensity and decay time dependences on europium concentration, and the influence of excitation power density on the cathodoluminescence of the sample. The most interesting result is the change of visible cathodoluminescence color in dependence on the density of the exciting power

  15. Mixed garnet laser crystals for water vapour DIAL transmitter

    Science.gov (United States)

    Treichel, Rainer; Czeranowsky, Christoph; Ileri, Bilge; Petermann, Klaus; Huber, Günter

    2017-11-01

    There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser. A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed. Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening. The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

  16. Laser ablation of Bi-substituted gadolinium iron garnet films

    International Nuclear Information System (INIS)

    Watanabe, N.; Hayashida, K.; Kawano, K.; Higuchi, K.; Ohkoshi, M.; Tsushima, K.

    1995-01-01

    Bi-substituted gadolinium iron garnet films were deposited by laser ablation. The composition, the structure and the magnetic properties of the films were found to be strongly dependent both on the compositions of the targets and on the pressure of oxygen. The highest values of Bi-substitution up to x=1.44 with uniform composition were obtained, after annealing in air. ((orig.))

  17. Recurrent thermo-luminescence phenomenon in yttrium-aluminum garnet crystals

    International Nuclear Information System (INIS)

    Islamov, A.Kh.; Nuritdinov, I.; Esanov, Z.U.; Eshchanov, B.Kh.; Khayitov, I.A.

    2014-01-01

    Full text : The crystals of yttrium-aluminum garnet Y 2 Al 2 O 1 2 activated by cerium and praseodymium ions by their thermal and chemical durability as well as fast response are perspective scintillation materials. In this work the capture centres formed by action of the ionizing radiation on pure and doped by praseodymium and cerium crystals were investigated. The samples were grown using Chokhralsky method

  18. Structural and magnetic properties of yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrites prepared by microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Akhtar, Majid Niaz, E-mail: majidniazakhtar@ciitlahore.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Bakar Sulong, Abu [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, G.C. University, Lahore, Pakistan" f Department of Mechanical Engineering, COMSATS Institute of Information Technology Sahiwal Pakistan (Pakistan); Raza, M.R. [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Mechanical Engineering, COMSATS Institute of Information Technology Sahiwal (Pakistan); Raza, R.; Saleem, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Kashif, M. [Department of Physics, Govt. College University Faisalabad (Pakistan)

    2016-03-01

    Yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrite samples were synthesized by microemulsion method. The effect of sintering was examined by heating the samples at 900, 1000, and 1100 °C. The YIG and YAIG samples were then characterized using X-ray diffraction and field-emission scanning electron microscopy. Static and dynamic magnetic properties were measured by evaluating initial permeability, Q factor, and vibrating sample magnetometry properties of YIG and YAIG samples. YIG samples sintered at 1100 °C showed higher initial permeability and Q factor compared with YAIG samples. However, hysteresis loops also showed variations in the saturation magnetization, remanence, and coercivity of YIG and YAIG samples sintered at 900, 1000, and 1100 °C. The observed magnetic parameter such as saturation magnetization, coercivity and initial permeability are strongly affected by increasing temperature. The saturation magnetization and coercivity of YIG and YAIG nanoferrites were found in the range 11.56–19.92 emu/g and 7.30–87.70 Oe respectively. Furthermore, the decreasing trends in the static and magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. Thus, YIG and YAIG sintered at 1100 °C can be used for wide-ranging frequency applications. - Highlights: • Static and dynamic magnetic properties of YIG and YAIG nanoferrites were determined. • Saturation magnetization, Q and initial permeability increased in YIG nanoferites. • Possible use of these nanoferrites for sensing and switching applications.

  19. Pattern analysis of laser-tattoo interactions for picosecond- and nanosecond-domain 1,064-nm neodymium-doped yttrium-aluminum-garnet lasers in tissue-mimicking phantom.

    Science.gov (United States)

    Ahn, Keun Jae; Zheng, Zhenlong; Kwon, Tae Rin; Kim, Beom Joon; Lee, Hye Sun; Cho, Sung Bin

    2017-05-08

    During laser treatment for tattoo removal, pigment chromophores absorb laser energy, resulting in fragmentation of the ink particles via selective photothermolysis. The present study aimed to outline macroscopic laser-tattoo interactions in tissue-mimicking (TM) phantoms treated with picosecond- and nanosecond-domain lasers. Additionally, high-speed cinematographs were captured to visualize time-dependent tattoo-tissue interactions, from laser irradiation to the formation of photothermal and photoacoustic injury zones (PIZs). In all experimental settings using the nanosecond or picosecond laser, tattoo pigments fragmented into coarse particles after a single laser pulse, and further disintegrated into smaller particles that dispersed toward the boundaries of PIZs after repetitive delivery of laser energy. Particles fractured by picosecond treatment were more evenly dispersed throughout PIZs than those fractured by nanosecond treatment. Additionally, picosecond-then-picosecond laser treatment (5-pass-picosecond treatment + 5-pass-picosecond treatment) induced greater disintegration of tattoo particles within PIZs than picosecond-then-nanosecond laser treatment (5-pass-picosecond treatment + 5-pass-nanosecond treatment). High-speed cinematography recorded the formation of PIZs after repeated reflection and propagation of acoustic waves over hundreds of microseconds to a few milliseconds. The present data may be of use in predicting three-dimensional laser-tattoo interactions and associated reactions in surrounding tissue.

  20. Dislocation of polyfocal full-optics accommodative intraocular lens after neodymium-doped yttrium aluminum garnet capsulotomy in vitrectomized eye

    Directory of Open Access Journals (Sweden)

    Kyung Tae Kang

    2013-01-01

    Full Text Available We report a case of dislocation of WIOL-CF® polyfocal full-optics intraocular lens (IOL after neodymium-doped yttrium aluminum garnet (Nd: YAG laser capsulotomy in the vitrectomized eye. At 22 months before the dislocation of the IOL, a 55-year-old male patient underwent phacoemulsification with WIOL-CF® IOL implantation in a local clinic and 10 months after the cataract surgery the patient underwent pars plana vitrectomy, endolaser photocoagulation and 14% C 3 F 8 gas tamponade for the treatment of rhegmatogenous retinal detachment. At 9 months after the vitrectomy, the patient visited our clinic for a sudden decrease of vision after Nd: YAG capsulotomy in the local clinic. On fundus examination, the dislocated IOL was identified and the Nd: YAG capsulotomy site and the larger break, which is suspected to have been a route of the dislocation were observed in the posterior capsule.

  1. Tattoo removal by Q-switched yttrium aluminium garnet laser

    DEFF Research Database (Denmark)

    Hutton Carlsen, K; Esmann, J; Serup, J

    2017-01-01

    BACKGROUND: Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. OBJECTIVE: To determine clients' satisfaction with tattoo removal. METHODS: One hundred and fifty-four tattoo removal clients who had...... relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate...

  2. Cerium-doped single crystal and transparent ceramic lutetium aluminum garnet scintillators

    International Nuclear Information System (INIS)

    Cherepy, Nerine J.; Kuntz, Joshua D.; Tillotson, Thomas M.; Speaks, Derrick T.; Payne, Stephen A.; Chai, B.H.T.; Porter-Chapman, Yetta; Derenzo, Stephen E.

    2007-01-01

    For rapid, unambiguous isotope identification, scintillator detectors providing high-resolution gamma ray spectra are required. We have fabricated Lutetium Aluminum Garnet (LuAG) using transparent ceramic processing, and report a 2-mm thick ceramic exhibiting 75% transmission and light yield comparable to single-crystal LuAG:Ce. The LuAG:Ce luminescence peaks at 550 nm, providing an excellent match for Silicon Photodiode readout. LuAG is dense (6.67 g/cm 3 ) and impervious to water, exhibits good proportionality and a fast decay (∼40 ns), and we measure light yields in excess of 20,000 photons/MeV

  3. Computational modelling of Er(3+): Garnet laser materials

    Science.gov (United States)

    Spangler, Lee H.

    1994-01-01

    The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

  4. Synthesis and luminescent study of Ce3+-doped terbium–yttrium aluminum garnet

    International Nuclear Information System (INIS)

    Dotsenko, V.P.; Berezovskaya, I.V.; Zubar, E.V.; Efryushina, N.P.; Poletaev, N.I.; Doroshenko, Yu.A.; Stryganyuk, G.B.; Voloshinovskii, A.S.

    2013-01-01

    Highlights: ► Ce 3+ -doped garnets (TYAG) were prepared using nanostructured reagents. ► The Ce 3+ ions cause a very efficient yellow emission of the samples. ► The reasons for the long wavelength position of this emission are discussed. ► Contribution from Al atoms to the conduction band of TYAG is quite essential. - Abstract: Terbium–yttrium aluminum garnets (TYAG) doped with Ce 3+ ions have been prepared by solid state reactions between nanostructured oxides of aluminum and rare earths. The luminescent properties of Ce 3+ ions in (Tb 0.8 Y 0.2 ) 3(1−x) Ce 3x Al 5 O 12 (x = 0.03) have been studied upon excitation in the 2–20 eV region. The substitution of Tb 3+ for Y 3+ in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f n → 4f n−1 5d excitation bands of Ce 3+ and Tb 3+ ions, the excitation spectra for the Ce 3+ emission contain broad bands at 6.73 and ∼9.5 eV. These bands are attributed to the Ce 3+ -bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. In contrast to the predictions based on the results of electronic structure calculations on Y 3 Al 5 O 12 and Tb 4 Al 2 O 9 , the threshold of interband transitions in TYAG is at high energies (⩾7.3 eV), and contributions from Al tetr and Al oct atoms to the conduction-band density of states are evaluated as quite essential.

  5. ELECTRON MICROSCOPIC INVESTIGATION OF YTTRIUM ALUMINUM GARNET POWDERS Y3AL5O12, SYNTHESIZED BY SOL–GEL METHOD

    Directory of Open Access Journals (Sweden)

    A. E. Baranchikov

    2015-09-01

    diffractometers, radiation λCu Kα. Carl Zeiss NVision 40 electron microscope was used for the study by scanning electron microscopy (SEM. The results indicate significant effects of additives in the original acetate - nitrate solutions on the size and morphology of the particles during the synthesis of powders of yttrium aluminum garnet by sol-gel method. Relatively large particles not susceptible to the mutual sintering were obtained by using ethylene glycol and ammonium lauryl sulfate as additives. Practical Relevance. Powders of yttrium aluminum garnet synthesized by the sol-gel method using ethylene glycol and ammonium lauryl sulfate as additives can be of the greatest interest for creation of YAG:Nd3+ laser ceramics.

  6. Absence of magnetic ordering and field-induced phase diagram in the gadolinium aluminum garnet

    Science.gov (United States)

    Florea, O.; Lhotel, E.; Jacobsen, H.; Knee, C. S.; Deen, P. P.

    2017-12-01

    The robustness of spin liquids with respect to small perturbations, and the way magnetic frustration can be lifted by slight changes in the balance between competing magnetic interactions, remains a rich and open issue. We address this question through the study of the gadolinium aluminum garnet Gd3Al5O12 , a related compound to the extensively studied Gd3Ga5O12 . We report on its magnetic properties at very low temperatures. We show that despite a freezing at about 300 mK, no magnetic transition is observed, suggesting the presence of a spin-liquid state down to the lowest temperatures, similarly to Gd3Ga5O12 , in spite of a larger ratio between exchange and dipolar interactions. Finally, the phase diagram as a function of field and temperature is strongly reminiscent of the one reported in Gd3Ga5O12 . This study reveals the robust nature of the spin-liquid phase for Gd ions on the garnet lattice, in stark contrast to Gd ions on the pyrochlore lattice for which a slight perturbation drives the compound into a range of magnetically ordered states.

  7. Fabrication of cerium-doped yttrium aluminum garnet thin films by a mist CVD method

    Energy Technology Data Exchange (ETDEWEB)

    Murai, Shunsuke, E-mail: murai@dipole7.kuic.kyoto-u.ac.jp; Sato, Takafumi; Yao, Situ; Kamakura, Ryosuke; Fujita, Koji; Tanaka, Katsuhisa

    2016-02-15

    We synthesized thin films, consisting of yttrium aluminum garnet doped with Ce{sup 3+} (YAG:Ce), using the mist chemical vapor deposition (CVD) method, which allows the fabrication of high-quality thin films under atmospheric conditions without the use of vacuum equipment. Under a deposition rate of approximately 1 μm/h, the obtained thin films had a typical thickness of 2 μm. The XRD analysis indicated that the thin films consisted of single-phase YAG:Ce. The Rutherford backscattering confirmed the stoichiometry; the composition of the film was determined to be (Y, Ce){sub 3}Al{sub 5}O{sub 12}, with a Ce content of Ce/(Y+Ce)=2.5%. The YAG:Ce thin films exhibited fluorescence due to the 5d–4f electronic transitions characteristic of the Ce ions occupying the eight-coordinated dodecahedral sites in the YAG lattice. - Highlights: • We have synthesized thin films of yttrium aluminum garnet doped with Ce{sup 3+} (YAG:Ce) by using a mist chemical vapor deposition (CVD) method for the first time. • The thickness of the single-phase and stoichiometric thin film obtained by 2 h deposition and following heat treatments is 2 μm. • The thin film is porous but optically transparent, and shows yellow fluorescence upon irradiation with a blue light. • Mist-CVD is a green and sustainable technique that allows fabrication of high-quality thin films at atmospheric conditions without vacuum equipment.

  8. Treatment of melasma with low fluence, large spot size, 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the treatment of melasma in Fitzpatrick skin types II-IV.

    Science.gov (United States)

    Brown, Alia S; Hussain, Mussarat; Goldberg, David J

    2011-12-01

    Melasma is a common condition affecting over six million American women. Treatment of dermal or combined melasma is difficult and does not respond well to conventional topical therapies. Various light sources have been used recently in the treatment of melasma including fractionated ablative and non-ablative lasers as well as intense pulse light. We report the use of low fluence, large spot size Q-switched, Nd:Yag laser for the treatment of melasma in skin types II-IV.

  9. Rare-earth antisites in lutetium aluminum garnets: influence on lattice parameter and Ce.sup.3+./sup. multicenter structure

    Czech Academy of Sciences Publication Activity Database

    Przybylińska, H.; Wittlin, A.; Ma, C.G.; Brik, M.G.; Kamińska, A.; Sybilski, P.; Zorenko, Yu.; Nikl, Martin; Gorbenko, V.; Fedorov, A.; Kučera, M.; Suchocki, A.

    2014-01-01

    Roč. 36, č. 9 (2014), s. 1515-1519 ISSN 0925-3467 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : garnets * scintillators * laser materials * phosphors Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.981, year: 2014

  10. Preparation, microstructure and properties of yttrium aluminum garnet fibers prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Li Chengshun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Zhang Yujun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: yujunzhangcn@sdu.edu.cn; Gong Hongyu; Zhang Jingde; Nie Lifang [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-01-15

    Yttrium aluminum garnet (YAG) fiber was prepared by sol-gel method using water as the solvent. The spinnable YAG sol was synthesized using Al powder, Y(CH{sub 3}COOH){sub 3}.4H{sub 2}O and HCl as precursors, polyethylene oxide as viscosity adjusting agent. Gel fibers with diameter of 5-10 {mu}m were prepared from the YAG sol by using centrifugal spinning technique. YAG crystalline fibers were obtained by drying gel fibers and heat-treating at selected temperature. TG/DTA analysis showed an exotherm at 906 deg. C attributed to formation of YAG phase and weight loss of 45% at 1000 deg. C. XRD and FT-IR analysis showed that phase-pure YAG can be formed at 900 deg. C, and no other intermediate was observed. The grain size of YAG fibers increased from 25 to 220 nm and tensile strength decreased rapidly from 970 to 380 MPa when the sintering temperature increased from 900 to 1550 deg. C.

  11. Yttrium aluminum garnet (YAG) obtained by rare-earth mixed oxide (RE2O3)

    International Nuclear Information System (INIS)

    Castro, D.F.; Daguano, J.K.M.F.; Rodrigues Junior, D.; Suzuki, P.A.; Silva, O.M.M.

    2010-01-01

    In this work, the substitution of commercial Y 2 O 3 by a rare earth mixed oxide, RE 2 O 3 , to form Yttrium aluminum Garnet-Y 3 Al 5 O 12 , was investigated. Al 2 O 3 :Y 2 O 3 and Al 2 O 3 :RE 2 O 3 powder-mixtures, in a molar ratio of 60:40, were milled and subsequently cold uniaxially-pressed. Compacts were sintered at 1000, 1400 or 1600 deg C, for 120 minutes. RE 2 O 3 oxide was characterized by high-resolution synchrotron X-ray diffraction (HRXRD) and compared to Y 2 O 3 . X-ray diffraction pattern of the RE 2 O 3 indicates a true solid solution formation. Rietveld refinement of the sintered YAG and (RE)AG reveled a similar crystal structure to the YAGs obtained by the use of Al 2 O 3 -Y 2 O 3 or Al 2 O 3 -RE 2 O 3 respectively. Microstructural analysis of both, YAG or (RE)AG, revealed similar grain sizes of about 2.5 μm besides mechanical properties, with hardness of 400HV and fracture toughness of 3.8MPa.m1/2. It could be, thus, demonstrated that pure Y 2 O 3 can be substituted by the rare-earth solid solution, RE 2 O 3 , in the formation YAGs, presenting similar microstructural and mechanical properties. (author)

  12. Defect-property correlations in garnet crystals. III. The electrical conductivity and defect structure of luminescent nickel-doped yttrium aluminum garnet

    International Nuclear Information System (INIS)

    Rotman, S.R.; Tuller, H.L.

    1987-01-01

    The conduction mechanisms in nickel-doped yttrium aluminum garnet (Ni:YAG) have been studied as a function of temperature and partial pressue of oxygen. ac conductivity and ionic transference measurements show that Ni:YAG is a mixed ionic-electronic conductor with an ionic mobility characterized by an activation energy of 2.0--2.2 eV. The reduction of Ni +3 to Ni +2 causes an increase in the oxygen vacancy concentration and a concurrent rise in the magnitude of the ionic conductivity. Codoping with zirconium, on the other hand, fixes the nickel in the divalent state, increases the n-type conductivity, and lowers the degree of ionic conductivity. A defect model is presented which is consistent with all of these observations

  13. ELECTRON MICROSCOPIC INVESTIGATION OF YTTRIUM ALUMINUM GARNET POWDERS Y3AL5O12, SYNTHESIZED BY SOL–GEL METHOD

    OpenAIRE

    A. E. Baranchikov; V. A. Maslov; S. V. Shcherbakov; V. A. Usachyov; N. E. Kononenko; P. P. Fedorov; K. V. Dukelskiy

    2015-01-01

    Subject of Study. The paper presents results of characterization for neodymium doped yttrium aluminum garnet nanopowders - YAG:Nd3+ by the method of scanning electronic microscopy. Method. Synthesis of YAG:Nd3+ was carried out by sol-gel method from nitrate or acetate - nitrate solutions with addition of some organic compounds and ammonia as well. Such substances were used as the source ones: oxides of neodymium and yttrium with the content of the basic substance equal to 99.999 %; organic co...

  14. Refractory metal superalloys: Design of yttrium aluminum garnet passivating niobium alloys

    Science.gov (United States)

    Bryan, David

    A systems-based approach, integrating computational modeling with experimental techniques to approach engineering problems in a time and cost efficient manner, was employed to design a Nb-based refractory superalloy for use at 1300°C. Ashby-type selection criteria for both thermodynamic and kinetic parameters were employed to identify a suitable protective oxide for Nb alloys. Yttrium aluminum garnet (YAG) was selected as the most promising candidate for its excellent combination of desirable properties. The alloy microstructural concept was based upon the gamma - gamma' nickel-based superalloys in which the multifunctional gamma' phase serves as both a creep strengthening dispersion and a source of reactive elements for oxide passivation. Candidate ternary Pd-Y-Al and Pt-Y-Al compounds were fabricated and characterized by XRD and DTA. Of the intermetallics studied, only PtYAl had a high enough melting point (1580°C) for use in an alloy operating at 1300°C. The alloy matrix design was based upon Wahl's extension of Wagner's criterion for protective oxidation, requiring a reduction of the product N ODO/DAl by 5 orders of magnitude relative to binary Nb-Al. A thermodynamic and kinetic analysis identified elements with large oxygen affinities as the most beneficial for reducing the magnitude of the quantity NOD O. Construction of a combined thermodynamic and mobility database identified increased Al solubility as the best approach for increasing D Al. Utilizing the thermodynamic and mobility databases, obtained from a combination of model alloys, oxidation experiments, and first principles calculations, theoretical designs predicted the large changes in solubility and transport parameters were achievable. Several prototype alloys were then fabricated and evaluated via oxidation tests at both 1300°C and 1100°C. YAG formation was demonstrated as part of multicomponent oxide scales in the alloys that exhibited the greatest reduction in oxidation rates. The oxidation

  15. Optical and magnetooptical properties of terbium–scandium–aluminum and terbium-containing (gallates and aluminates) garnets

    Energy Technology Data Exchange (ETDEWEB)

    Valiev, Uygun V. [Faculty of Physics, National University of Uzbekistan, Vuzgorodok, Tashkent 100174 (Uzbekistan); Gruber, John B. [Department of Physics, San Jose State University, retired, San Jose, CA 95192 (United States); Burdick, Gary W. [Department of Physics, Andrews University, Berrien Springs, MI 49104 (United States); Ivanov, Igor’ A. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Fu, Dejun, E-mail: djfu@whu.edu.cn [School of Physics and Technology, Wuhan University, 430072 Wuhan (China); Pelenovich, Vasiliy O. [School of Physics and Technology, Wuhan University, 430072 Wuhan (China); Juraeva, Nafisa I. [Faculty of Physics, National University of Uzbekistan, Vuzgorodok, Tashkent 100174 (Uzbekistan)

    2016-08-15

    Comparative measurements of the Faraday rotation in Tb{sub 3}Ga{sub 5}O{sub 12} (TGG) and Tb{sub 3}Sc{sub 2–x}Al{sub 3+x}O{sub 12} (TSAG) garnets shows the values of the Verdet constant for TSAG are about 25% higher than that of TGG in the wavelength range 400–700 nm at the temperatures T=95 and 300 K. The increase of the Verdet constant is explained by increase of the “paramagnetic” frequency factor caused by the shift of the resonance frequency of the first allowed 4f→5d transition to the area of the lower frequencies in UV. The shift and observed strong broadening of the UV absorption bands in TSAG are explained by significant modification of the crystalline environment of the Tb{sup 3+} ion in this garnet. A comparison of the data of the C/D ratio in TSAG with the value of the magnetic moment of the Tb{sup 3+} ground state in Tb{sub 3}Al{sub 5}O{sub 12} (TAG) determined from magnetic measurements, showed an acceptable agreement for these parameters measured by fundamentally different methods. Measurements of the visible emission spectra reveal a strong influence of some disordering of the crystal field (CF) in TSAG in comparison with the terbium–aluminum garnet spectra. Magnetooptical effects of the intensity change of the luminescence lines in TSAG is caused by modification of the electronic structure of the {sup 5}D{sub 4} and {sup 7}F{sub 5} multiplets by Sc{sup 3+} ions in the lattice, leading to a local symmetry reduction of the Tb{sup 3+} ion in TSAG.

  16. Comparative evaluation of photoablative efficacy of erbium: yttrium-aluminium-garnet and diode laser for the treatment of gingival hyperpigmentation. A randomized split-mouth clinical trial.

    Science.gov (United States)

    Giannelli, Marco; Formigli, Lucia; Bani, Daniele

    2014-04-01

    The use of lasers in periodontology is a matter of debate, mainly because of the lack of consensual therapeutic protocols. In this randomized, split-mouth trial, the clinical efficacy of two different photoablative dental lasers, erbium:yttrium-aluminum-garnet (Er:YAG) and diode, for the treatment of gingival hyperpigmentation is compared. Twenty-one patients requiring treatment for mild-to-severe gingival hyperpigmentation were enrolled. Maxillary or mandibular left or right quadrants were randomly subjected to photoablative deepithelialization with either Er:YAG or diode laser. Masked clinical assessments of each laser quadrant were made at admission and days 7, 30, and 180 postoperatively by an independent observer. Histologic examination was performed before and soon after treatment and 6 months after irradiation. Patients also compiled a subjective evaluation questionnaire. Both diode and Er:YAG lasers gave excellent results in gingival hyperpigmentation. However, Er:YAG laser induced deeper gingival tissue injury than diode laser, as judged by bleeding at surgery, delayed healing, and histopathologic analysis. The use of diode laser showed additional advantages compared to Er:YAG in terms of less postoperative discomfort and pain. This study highlights the efficacy of diode laser for photoablative deepithelialization of hyperpigmented gingiva. It is suggested that this laser can represent an effective and safe therapeutic option for gingival photoablation.

  17. Diode laser welding of aluminum to steel

    International Nuclear Information System (INIS)

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-01-01

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  18. Microchip laser operation of Yb-doped gallium garnets

    Czech Academy of Sciences Publication Activity Database

    Serres, J.M.; Jambunathan, Venkatesan; Loiko, P.; Mateos, X.; Yu, H.; Zhang, H.; Liu, J.; Lucianetti, Antonio; Mocek, Tomáš; Yumashev, K.; Griebner, U.; Petrov, V.; Aguilo, M.; Diaz, F.

    2016-01-01

    Roč. 6, č. 1 (2016), s. 46-57 ISSN 2159-3930 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : thermal-conductivity * crystal * temperature * Y 3 AL 5 O 12 * YAG * performance * CNGG Subject RIV: BH - Optics, Masers, Laser s OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 2.591, year: 2016

  19. Erbium-doped yttrium aluminium garnet ablative laser treatment for endogenous ochronosis.

    Science.gov (United States)

    Chaptini, Cassandra; Huilgol, Shyamala C

    2015-08-01

    Ochronosis is a rare disease characterised clinically by bluish-grey skin discolouration and histologically by yellow-brown pigment deposits in the dermis. It occurs in endogenous and exogenous forms. Endogenous ochronosis, also known as alkaptonuria, is an autosomal recessive disease of tyrosine metabolism, resulting in the accumulation and deposition of homogentisic acid in connective tissue. We report a case of facial endogenous ochronosis and coexistent photodamage, which was successfully treated with erbium-doped yttrium aluminium garnet laser resurfacing and deep focal point treatment to remove areas of residual deep pigment. © 2014 The Australasian College of Dermatologists.

  20. Optical Characterizations of Surface Polished Polycrystalline YAG (Yttrium Aluminum Garnet) Fibers (Postprint)

    Science.gov (United States)

    2017-06-02

    potential alternative for higher power lasers. Eye- safe lasers with mid-IR range are used for biomedical applications, remote sensing, defense, etc.15...LiYF4, LiLuF4, BaY2F8, KGd(WO4)2, and KY(WO4)2 laser crystals in the 80-300 K temperature range,” J. Appl . Phys., 98 103514 (2005). [5] Slack, G. A...Laser damage threshold of ceramic YAG,” Jpn. J. Appl . Phys. 42, L1025 (2003). [7] Yoshida, K., Umemura, N., Kuzuu, N., Yoshida, H., Kamimura, T. and

  1. Higher Temperature Thermal Barrier Coatings with the Combined Use of Yttrium Aluminum Garnet and the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Wang, Jiwen; Kumar, Rishi; Roth, Jeffery; Jiang, Chen; Jordan, Eric H.

    2018-02-01

    Gas-turbine engines are widely used in transportation, energy and defense industries. The increasing demand for more efficient gas turbines requires higher turbine operating temperatures. For more than 40 years, yttria-stabilized zirconia (YSZ) has been the dominant thermal barrier coating (TBC) due to its outstanding material properties. However, the practical use of YSZ-based TBCs is limited to approximately 1200 °C. Developing new, higher temperature TBCs has proven challenging to satisfy the multiple property requirements of a durable TBC. In this study, an advanced TBC has been developed by using the solution precursor plasma spray (SPPS) process that generates unique engineered microstructures with the higher temperature yttrium aluminum garnet (YAG) to produce a TBC that can meet and exceed the major performance standards of state-of-the-art air plasma sprayed YSZ, including: phase stability, sintering resistance, CMAS resistance, thermal cycle durability, thermal conductivity and erosion resistance. The temperature improvement for hot section gas turbine materials (superalloys & TBCs) has been at the rate of about 50 °C per decade over the last 50 years. In contrast, SPPS YAG TBCs offer the near-term potential of a > 200 °C improvement in temperature capability.

  2. Numerical Simulation of Yttrium Aluminum Garnet(YAG) Single Crystal Growth by Resistance Heating Czochralski(CZ) Method

    Energy Technology Data Exchange (ETDEWEB)

    You, Myeong Hyeon; Cha, Pil Ryung [Kookmin University, Seoul (Korea, Republic of)

    2017-01-15

    Yttrium Aluminum Garnet (YAG) single crystal has received much attention as the high power solid-state laser’s key component in industrial and medical applications. Various growth methods have been proposed, and currently the induction-heating Czochralski (IHCZ) growth method is mainly used to grow YAG single crystal. Due to the intrinsic properties of the IHCZ method, however, the solid/liquid interface has a downward convex shape and a sharp tip at the center, which causes a core defect and reduces productivity. To produce YAG single crystals with both excellent quality and higher yield, it is essential to control the core defects. In this study, using computer simulations we demonstrate that the resistance-heating CZ (RHCZ) method may avoid a downward convex interface and produce core defect free YAG single crystal. We studied the effects of various design parameters on the interface shape and found that there was an optimum combination of design parameter and operating conditions that produced a flat solid-liquid interface.

  3. Higher Temperature Thermal Barrier Coatings with the Combined Use of Yttrium Aluminum Garnet and the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Wang, Jiwen; Kumar, Rishi; Roth, Jeffery; Jiang, Chen; Jordan, Eric H.

    2018-04-01

    Gas-turbine engines are widely used in transportation, energy and defense industries. The increasing demand for more efficient gas turbines requires higher turbine operating temperatures. For more than 40 years, yttria-stabilized zirconia (YSZ) has been the dominant thermal barrier coating (TBC) due to its outstanding material properties. However, the practical use of YSZ-based TBCs is limited to approximately 1200 °C. Developing new, higher temperature TBCs has proven challenging to satisfy the multiple property requirements of a durable TBC. In this study, an advanced TBC has been developed by using the solution precursor plasma spray (SPPS) process that generates unique engineered microstructures with the higher temperature yttrium aluminum garnet (YAG) to produce a TBC that can meet and exceed the major performance standards of state-of-the-art air plasma sprayed YSZ, including: phase stability, sintering resistance, CMAS resistance, thermal cycle durability, thermal conductivity and erosion resistance. The temperature improvement for hot section gas turbine materials (superalloys & TBCs) has been at the rate of about 50 °C per decade over the last 50 years. In contrast, SPPS YAG TBCs offer the near-term potential of a > 200 °C improvement in temperature capability.

  4. Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

    International Nuclear Information System (INIS)

    Cho, Joong-yeon; Park, Sang-Jun; Ahn, Jinho; Lee, Heon

    2014-01-01

    In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%

  5. Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Joong-yeon; Park, Sang-Jun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Ahn, Jinho, E-mail: jhahn@hanyang.ac.kr [Department of Material Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2014-11-03

    In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%.

  6. Tattoo removal by Q-switched yttrium aluminium garnet laser: client satisfaction.

    Science.gov (United States)

    Hutton Carlsen, K; Esmann, J; Serup, J

    2017-05-01

    Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. To determine clients' satisfaction with tattoo removal. One hundred and fifty-four tattoo removal clients who had attended the private clinic 'Centre for Laser Surgery', Hellerup, Denmark, from 2001 to 2013 completed a questionnaire concerning outcome expectations, level of pain experiences and satisfaction with tattoo removal. The laser surgeon and his team were blinded from data handling. The study design included a minimum 2-year postlaser treatment observation period from 2013 to 2015. Overall, clients were satisfied with their laser treatment; 85% assessed their treatment and results to be acceptable to superb, while 15% assessed their treatment and results to be inferior to unacceptable. Effectiveness relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate to extreme pain during treatment. Twenty-eight (20%) developed minor scarring. There were many reasons for tattoo removal; e.g. stigmatisation (33%), conspicuousness (29%) and poor artistic quality (22%). One hundred and two clients had expected complete removal of tattoos without a blemish, expectations that were only partly fulfilled. During the treatment period, clients adjusted expectations and adapted more realistic views of outcomes. The majority of clients were satisfied with Q-switched YAG laser removal of tattoos despite high pretreatment expectations which were only partly met. The study supports YAG lasers for tattoo removal as acceptable therapy of today, with room for new approaches. © 2017 European Academy of Dermatology and Venereology.

  7. Comparison between 0.5% timolol maleate and 0.2% brimonidine tartrate in controlling increase in intraocular pressure after neodymium: yttrium-aluminium-garnet laser capsulotomy

    International Nuclear Information System (INIS)

    Tayyab, H.; Azhar, M.N.; Haider, M.A.; Jahangir, T.

    2013-01-01

    Objective: To compare the effectiveness of prophylactically given 0.5% Timolol maleate and 0.2% Brimonidine tartrate in controlling increase in intraocular pressure after neodymium (Nd) : yttrium aluminum garnet (YAG) laser capsulotomy. Study Design: Randomized controlled trial. Place and Duration of Study: This study was conducted at Ophthalmology Department, Jinnah Hospital, Lahore from 15-05-2009 to 14-05-2010 for a duration of 12 months. Material and Methods: In this study, 90 consecutive patients were referred from outpatient department for Nd: YAG laser capsulotomy. Hospital ethical committee's approval for this research proposal and the informed consent was taken. These patients were equally divided into two groups A and B, comprising of 45 patients in each group. Group A was control group which received 0.5% Timolol maleate. Group B was experimental group which received 0.2% Brimonidine tartrate. Intraocular pressure was measured using Goldmann tonometer before instilling these topical medications. These medications were administered topically 1 hour before the laser procedure. Intraocular pressure (IOP) was recorded 1 and 3 hours after laser capsulotomy. Results: In patients belonging to group A, 42 (93.3%) patients had effective control of IOP (raise of less than or equal to 5 mmHg from the baseline) after 3 hours of Nd:YAG laser capsulotomy whereas 28 (62.2%) patients had effective control of IOP after the same period of time in group-B with significant difference (p<0.001). Conclusion: Use of prophylactic topical antiglaucoma medications before doing Nd: YAG laser capsulotomy is a effective way to reduce post laser spike of intraocular pressure. Present study showed that the use of 0.5% timolol maleate was safe and more effective than 0.2% brimonidine tartrate when given 1 hour before laser capsulotomy. (author)

  8. Coloration of chromium-doped yttrium aluminum garnet single-crystal fibers using a divalent codopant

    International Nuclear Information System (INIS)

    Tissue, B.M.; Jia, W.; Lu, L.; Yen, W.M.

    1991-01-01

    We have grown single-crystal fibers of Cr:YAG and Cr,Ca:YAG under oxidizing and reducing conditions by the laser-heated-pedestal-growth method. The Cr:YAG crystals were light green due to Cr 3+ in octahedral sites, while the Cr,Ca:YAG crystals were brown. The presence of the divalent codopant was the dominant factor determining the coloration in these single-crystal fibers, while the oxidizing power of the growth atmosphere had little effect on the coloration. The Cr,Ca:YAG had a broad absorption band centered at 1.03 μm and fluoresced from 1.1 to 1.7 μm, with a room-temperature lifetime of 3.5 μs. The presence of both chromium and a divalent codopant were necessary to create the optically-active center which produces the near-infrared emission. Doping with only Ca 2+ created a different coloration with absorption in the blue and ultraviolet. The coloration in the Cr,Ca:YAG is attributed to Cr 4+ and is produced in as-grown crystals without irradiation or annealing, as has been necessary in previous work

  9. Surface melting technique of small diameter stainless steel pipe by means of yttrium aluminium garnet laser

    International Nuclear Information System (INIS)

    Katahira, Fujito; Hirano, Kenji; Tanaka, Yasuhiro; Yoshida, Kazuo; Kuribayashi, Munetaka; Umemoto, Tadahiro

    1994-01-01

    A new method of surface melting by using a high power yttrium aluminium garnet laser was developed. This method is applicable to a long distance and narrow space, because of the good accessibility of the laser beam through optical fibre.A desensitization of sensitized type 304 stainless steel pipe was demonstrated by using this technique. A melted layer of thickness approximately 200μm had a very finite solidification structure, which contained approximately 1.5% δ-ferrite. The average chemical composition of this layer was almost the same as that of type 304 stainless steel, and a band of 300μm thickness under the melted layer underwent solution heat treatment (SHT).As a result of such surface melting, the melted layer exhibited superior resistance to intergranular stress corrosion cracking (IGSCC). Since the SHT layer is highly resistant to IGSCC generally, it may be possible to improve the IGSCC resistance of base metal to a comparatively deep extent (500μm from the surface) by this technique. ((orig.))

  10. Surface melting technique of small diameter stainless steel pipe by means of yttrium aluminium garnet laser

    Energy Technology Data Exchange (ETDEWEB)

    Katahira, Fujito (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan)); Hirano, Kenji (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan)); Tanaka, Yasuhiro (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan)); Yoshida, Kazuo (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan)); Kuribayashi, Munetaka (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan)); Umemoto, Tadahiro (Ishikawajima-Harima Heavy Industries Co. Ltd., 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235 (Japan))

    1994-12-01

    A new method of surface melting by using a high power yttrium aluminium garnet laser was developed. This method is applicable to a long distance and narrow space, because of the good accessibility of the laser beam through optical fibre.A desensitization of sensitized type 304 stainless steel pipe was demonstrated by using this technique. A melted layer of thickness approximately 200[mu]m had a very finite solidification structure, which contained approximately 1.5% [delta]-ferrite. The average chemical composition of this layer was almost the same as that of type 304 stainless steel, and a band of 300[mu]m thickness under the melted layer underwent solution heat treatment (SHT).As a result of such surface melting, the melted layer exhibited superior resistance to intergranular stress corrosion cracking (IGSCC). Since the SHT layer is highly resistant to IGSCC generally, it may be possible to improve the IGSCC resistance of base metal to a comparatively deep extent (500[mu]m from the surface) by this technique. ((orig.))

  11. Thermal effects from modified endodontic laser tips used in the apical third of root canals with erbium-doped yttrium aluminium garnet and erbium, chromium-doped yttrium scandium gallium garnet lasers.

    Science.gov (United States)

    George, Roy; Walsh, Laurence J

    2010-04-01

    To evaluate the temperature changes occurring on the apical third of root surfaces when erbium-doped yttrium aluminium garnet (Er:YAG) and erbium, chromium-doped yttrium scandium gallium garnet (Er,Cr:YSGG) laser energy was delivered with a tube etched, laterally emitting conical tip and a conventional bare design optical fiber tip. Thermal effects of root canal laser treatments on periodontal ligament cells and alveolar bone are of concern in terms of safety. A total of 64 single-rooted extracted teeth were prepared 1 mm short of the working length using rotary nickel-titanium Pro-Taper files to an apical size corresponding to a F5 Pro-Taper instrument. A thermocouple located 2 mm from the apex was used to record temperature changes arising from delivery of laser energy through laterally emitting conical tips or plain tips, using an Er:YAG or Er,Cr:YSGG laser. For the Er:YAG and Er,Cr:YSGG systems, conical fibers showed greater lateral emissions (452 + 69% and 443 + 64%) and corresponding lower forward emissions (48 + 5% and 49 + 5%) than conventional plain-fiber tips. All four combinations of laser system and fiber design elicited temperature increases less than 2.5 degrees C during lasing. The use of water irrigation attenuated completely the thermal effects of individual lasing cycles. Laterally emitting conical fiber tips can be used safely under defined conditions for intracanal irradiation without harmful thermal effects on the periodontal apparatus.

  12. Low-relaxation spin waves in laser-molecular-beam epitaxy grown nanosized yttrium iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Lutsev, L. V., E-mail: l-lutsev@mail.ru; Korovin, A. M.; Bursian, V. E.; Gastev, S. V.; Fedorov, V. V.; Suturin, S. M.; Sokolov, N. S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2016-05-02

    Synthesis of nanosized yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10{sup −5}. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

  13. Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization

    Directory of Open Access Journals (Sweden)

    M. C. Onbasli

    2014-10-01

    Full Text Available Yttrium iron garnet (YIG, Y 3Fe5O12 films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd3Ga5O12 substrates with (100 orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe, near-bulk room temperature saturation moments (∼135 emu cm−3, in-plane easy axis, and damping parameters as low as 2.2 × 10−4. These high quality YIG thin films are useful in the investigation of the origins of novel magnetic phenomena and magnetization dynamics.

  14. A randomized controlled trial of peeling and aspiration of Elschnig pearls and neodymium: yttrium-aluminium-garnet laser capsulotomy.

    Science.gov (United States)

    Bhargava, Rahul; Kumar, Prachi; Sharma, Shiv Kumar; Kaur, Avinash

    2015-01-01

    To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification (PCO). A prospective, randomized, double blind, study was done at Rotary Eye Hospital, Maranda, Palampur, India, Santosh Medical College Hospital, Ghaziabad, India and Laser Eye Clinic, Noida India. Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction (ECCE) for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity (CDVA), intra-operative and post-operative complications were compared. A total of 634 patients participated in the study, and 314 (49.5%) patients were randomized to surgical peeling and aspiration group and 320 (50.5%) to the Nd:YAG laser group. The mean pre-procedural logMAR CDVA in peeling and neodymium: yttrium-aluminium-garnet (Nd:YAG) laser group was 0.80±0.25 and 0.86±0.22, respectively. The mean final CDVA in peeling group (0.22±0.23) was comparable to Nd:YAG group (0.24±0.28; t test, P=0.240). There was a significant improvement in vision after both the procedures (Ppeeling group (262/83.4%) had a CDVA of 0.5 (20/63) or better at 9mo (Ppeeling group (25/7.7% vs 15/4.7%, respectively). On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001 % risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group, thick PCO had a stronger impact on complications (Fischer test probability, Prpeeling group, thick PCO and preoperative vision had a stronger effect on complications than thin PCO, respectively (Fischer test probability, Prpeeling group. Retinal detachment was more common in patients

  15. Energy resolution studies of Ce- and Pr-doped aluminum and multicomponent garnets: the escape and photo-peaks

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří A.; Beitlerová, Alena; Průša, Petr; Blažek, K.; Horodysky, P.; Kamada, K.; Yoshikawa, A.; D'Ambrosio, C.; Nikl, Martin

    2016-01-01

    Roč. 169, Jan (2016), s. 701-705 ISSN 0022-2313. [International Conference on Luminescence and Optical Spectroscopy of Condensed Matter /17./. Wroclaw, 13.07.2014-18.07.2014] R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : multicomponent garnets * energy resolution * photo and escape peaks * Ce and Pr dopants * pulse height spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.686, year: 2016

  16. A randomized controlled trial of peeling and aspiration of Elschnig pearls and neodymium:yttrium-aluminium-garnet laser capsulotomy

    Directory of Open Access Journals (Sweden)

    Rahul Bhargava

    2015-06-01

    Full Text Available AIM:To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification (PCO.METHODS:A prospective, randomized, double blind, study was done at Rotary Eye Hospital, Maranda, Palampur, India, Santosh Medical College Hospital, Ghaziabad, India and Laser Eye Clinic, Noida India. Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction (ECCE for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity (CDVA, intra-operative and post-operative complications were compared.RESULTS:A total of 634 patients participated in the study, and 314 (49.5% patients were randomized to surgical peeling and aspiration group and 320 (50.5% to the Nd:YAG laser group. The mean pre-procedural logMAR CDVA in peeling and neodymium:yttrium-aluminium-garnet (Nd:YAG laser group was 0.80±0.25 and 0.86±0.22, respectively. The mean final CDVA in peeling group (0.22±0.23 was comparable to Nd:YAG group (0.24±0.28; t test, P=0.240. There was a significant improvement in vision after both the procedures (P<0.001. A slightly higher percentage of patients in Nd:YAG laser group (283/88.3% than in peeling group (262/83.4% had a CDVA of 0.5 (20/63 or better at 9mo (P<0.001. On the contrary, patients having CDVA worse than 1.00 (20/200 was also significantly higher in Nd:YAG laser group as compared to peeling group (25/7.7% vs 15/4.7%, respectively. On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001 % risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group, thick PCO had a stronger impact

  17. Controlling laser-induced magnetization reversal dynamics in a rare-earth iron garnet across the magnetization compensation point

    Science.gov (United States)

    Deb, Marwan; Molho, Pierre; Barbara, Bernard; Bigot, Jean-Yves

    2018-04-01

    In this work we explore the ultrafast magnetization dynamics induced by femtosecond laser pulses in a doped film of gadolinium iron garnet over a broad temperature range including the magnetization compensation point TM. By exciting the phonon-assisted 6S→4G and 6S→4P electronic d -d transitions simultaneously by one- and two-photon absorption processes, we find out that the transfer of heat energy from the lattice to the spin has, at a temperature slightly below TM, a large influence on the magnetization dynamics. In particular, we show that the speed and the amplitude of the magnetization dynamics can be strongly increased when increasing either the external magnetic field or the laser energy density. The obtained results are explained by a magnetization reversal process across TM. Furthermore, we find that the dynamics has unusual characteristics which can be understood by considering the weak spin-phonon coupling in magnetic garnets. These results open new perspectives for controlling the magnetic state of magnetic dielectrics using an ultrashort optically induced heat pulse.

  18. Investigations on dry sliding of laser cladded aluminum bronze

    Directory of Open Access Journals (Sweden)

    Freiße Hannes

    2016-01-01

    Full Text Available The aim of this study was to investigate the tribological behaviour of laser cladded aluminum bronze tool surfaces for dry metal forming. In a first part of this work a process window for cladding aluminum bronze on steel substrate was investigated to ensure a low dilution. Therefore, the cladding speed, the powder feed rate, the laser power and the distance between the process head and the substrate were varied. The target of the second part was to investigate the influence of different process parameters on the tribological behaviour of the cladded tracks. The laser claddings were carried out on both aluminum bronze and cold work tool steel as substrate materials. Two different particle sizes of the cladding powder material were used. The cladding speed was varied and a post-processing laser remelting treatment was applied. It is shown that the tribological behaviour of the surface in a dry oscillating ball-on-plate test is highly dependent on the substrate material. In the third part a deep drawing tool was additively manufactured by direct laser deposition. Furthermore, the tool was applied to form circular cups with and without lubrication.

  19. High-pressure optical spectroscopy and X-ray diffraction studies on synthetic cobalt aluminum silicate garnet

    DEFF Research Database (Denmark)

    N. Taran, Michail; Nestola, Fabrizio; Ohashi, Haruo

    2007-01-01

    The pressure-induced behavior of spin-allowed dd-bands of VIIICo2+ in the absorption spectra of synthetic Co3Al2Si3O12 garnet was studied from 10-4 to 13 GPa. The plots of the peak energy vs. pressure for the three sharpest well resolved bands at ca. 5160, 17 680, and 18 740 cm-1 display small...... but discernible breaks in linear relations between 4 and 5 GPa. Datafromsingle-crystalX-raydiffractionData from single-crystal X-ray diffraction likewise show discontinuities in trends of CoO8 polyhedral volume and distortion, and Co-O and Si-O bond distances over this pressure range. These effects are related...... to a pressure-induced phase transition from the ß- to a-isostructural polymorph of Co3Al2Si3O12....

  20. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, N. S., E-mail: nsokolov@fl.ioffe.ru; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V. [Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Maksimova, K. Yu.; Grunin, A. I. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Tabuchi, M. [Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603 (Japan)

    2016-01-14

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y{sub 3}Fe{sub 5}O{sub 12} (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

  1. Thin yttrium iron garnet films grown by pulsed laser deposition: Crystal structure, static, and dynamic magnetic properties

    International Nuclear Information System (INIS)

    Sokolov, N. S.; Fedorov, V. V.; Korovin, A. M.; Suturin, S. M.; Baranov, D. A.; Gastev, S. V.; Krichevtsov, B. B.; Bursian, V. E.; Lutsev, L. V.; Maksimova, K. Yu.; Grunin, A. I.; Tabuchi, M.

    2016-01-01

    Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films

  2. Aluminum alloy nanosecond vs femtosecond laser marking

    Indian Academy of Sciences (India)

    Faculty of Materials Science and Engineering, Technical University “Gheorghe Asachi” of Iasi, No. ... molten material. One can identify local melting of circular shape, subsequently solidified with partial superimposing of molten alloy. The laser writing presents a ... Abbott–Firestone curve (Abbott and Firestone 1933), which.

  3. Laser shock wave consolidation of nanodiamond powders on aluminum 319

    Energy Technology Data Exchange (ETDEWEB)

    Molian, Pal [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)], E-mail: molian@iastate.edu; Molian, Raathai; Nair, Rajeev [Laboratory for Lasers, MEMS, and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)

    2009-01-01

    A novel coating approach, based on laser shock wave generation, was employed to induce compressive pressures up to 5 GPa and compact nanodiamond (ND) powders (4-8 nm) on aluminum 319 substrate. Raman scattering indicated that the coating consisted of amorphous carbon and nanocrystalline graphite with peaks at 1360 cm{sup -1} and 1600 cm{sup -1} respectively. Scanning electron microscopy revealed a wavy, non-uniform coating with an average thickness of 40 {mu}m and absence of thermal effect on the surrounding material. The phase transition from nanodiamond to other phases of carbon is responsible for the increased coating thickness. Vicker's microhardness test showed hardness in excess of 1000 kg{sub f}/mm{sup 2} (10 GPa) while nanoindentation test indicated much lower hardness in the range of 20 MPa to 2 GPa. Optical surface profilometry traces displayed slightly uneven surfaces compared to the bare aluminum with an average surface roughness (R{sub a}) in the range of 1.5-4 {mu}m depending on the shock wave pressure and type of confining medium. Ball-on-disc tribometer tests showed that the coefficient of friction and wear rate were substantially lower than the smoother, bare aluminum sample. Laser shock wave process has thus aided in the generation of a strong, wear resistant, durable carbon composite coating on aluminum 319 substrate.

  4. Aluminum alloy analysis using microchip-laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, Andrew [Center for Sensor Systems and Technologies, Aerodyne Research, Inc., 45 Manning Road Billerica, MA, 01821-3976 (United States)]. E-mail: af@aerodyne.com; Iannarilli, Frank J. [Center for Sensor Systems and Technologies, Aerodyne Research, Inc., 45 Manning Road Billerica, MA, 01821-3976 (United States); Wormhoudt, Joda C. [Center for Sensor Systems and Technologies, Aerodyne Research, Inc., 45 Manning Road Billerica, MA, 01821-3976 (United States)

    2005-08-31

    A laser induced breakdown spectroscopy-based apparatus for the analysis of aluminum alloys which employs a microchip laser and a handheld spectrometer with an ungated, non-intensified CCD array has been built and tested. The microchip laser, which emits low energy pulses (4-15 {mu}J) at high repetition rates (1-10 kHz) at 1064 nm, produces, when focused, an ablation crater with a radius on the order of only 10 {mu}m. The resulting emission is focused onto an optical fiber connected to 0.10 m focal length spectrometer with a spectral range of 275-413 nm. The apparatus was tested using 30 different aluminum alloy reference samples. Two techniques for constructing calibration curves from the data, peak integration and partial least squares regression, were quantitatively evaluated. Results for Fe, Mg, Mn, Ni, Si, and Zn indicated limits of detection (LOD) that ranged from 0.05 to 0.14 wt.% and overall measurement errors which varied from 0.06 to 0.18 wt.%. Higher limits of detection and overall error for Cu (> 0.3 wt.%) were attributed to analysis problems associated with the presence of optically thick lines and a spectral interference from Zn. Improvements in design and component sensitivity should increase overall performance by at least a factor of 2, allowing for dependable aluminum alloy classification.

  5. Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

    Science.gov (United States)

    Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

    2018-04-01

    In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

  6. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  7. Supersonic laser-induced jetting of aluminum micro-droplets

    International Nuclear Information System (INIS)

    Zenou, M.; Sa'ar, A.; Kotler, Z.

    2015-01-01

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets

  8. Industrial garnet

    Science.gov (United States)

    Olson, D.W.

    2000-01-01

    The state of the global industrial garnet industry in 1999 is discussed. Industrial garnet mined in the U.S., which accounts for approximately one-third of the world's total, is usually a solid-solution of almandine and pyrope. The U.S. is the largest consumer of industrial garnet, using an estimated 47,800 st in 1999 as an abrasive and as a filtration medium in the petroleum industry, filtration plants, aircraft and motor vehicle manufacture, shipbuilding, wood furniture finishing operations, electronic component manufacture, ceramics manufacture, and glass production. Prices for crude concentrates ranged from approximately $50 to $110/st and refined garnet from $50 to $215/st in 1999, depending on type, source, quantity purchased, quality, and application.

  9. Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

    Science.gov (United States)

    1989-09-01

    at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

  10. A thermal model for nanosecond pulsed laser ablation of aluminum

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2017-07-01

    Full Text Available In order to simulate the nanosecond pulsed laser ablation of aluminum, a novel model was presented for the target ablation and plume expansion. The simulation of the target ablation was based on one-dimensional heat conduction, taking into account temperature dependent material properties, phase transition, dielectric transition and phase explosion. While the simulation of the plume expansion was based on one-dimensional gas-dynamical equation, taking into account ionization, plume absorption and shielding. By coupling the calculations of the target ablation and plume expansion, the characteristics of the target and plume were obtained. And the calculated results were in good agreement with the experimental data, in terms of ablation threshold and depth within the fluence range of the tested laser. Subsequently, investigations were carried out to analyze the mechanisms of nanosecond pulsed laser ablation. The calculated results showed that the maximum surface temperature remained at about 90% of the critical temperature (0.9Tc due to phase explosion. Moreover, the plume shielding has significant effects on the laser ablation, and the plume shielding proportion increase as the laser fluence increasing. The ambient pressure belows 100 Pa is more suitable for laser ablation, which can obtained larger ablation depth.

  11. Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser ...

    African Journals Online (AJOL)

    2016-03-29

    etched dentin surface showed opened dentinal tubule with a ... Department of Pediatric Dentistry, Faculty of Dentistry, ... decrease the bonding ability of composite resins to .... Sixty extracted sound human mandibular molars were.

  12. Effect of Erbium:yttrium Aluminum Garnet Laser on Bond Strength of ...

    African Journals Online (AJOL)

    2017-06-28

    Jun 28, 2017 ... leakage have been shown in vitro in cavities with the cervical margin ... that used a water‑based adhesive in Class II preparations found that the bond .... than 80% power to detect significant differences with a. 0.58 effect size ...

  13. Percutaneous yttrium aluminum garnet-laser lithotripsy of intrahepatic stones and casts after liver transplantation

    DEFF Research Database (Denmark)

    Schlesinger, Nis Hallundbaek; Svenningsen, Peter; Frevert, Susanne

    2015-01-01

    % needed additional interventions in the form of percutaneous transhepatic cholangiography and dilation (17%), re-PTCSL (11%), self-expandable metallic stents (22%), or hepaticojejunostomy (6%); and 22% eventually underwent retransplantation. The overall liver graft survival rate was 78%. Two patients died...

  14. Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser ...

    African Journals Online (AJOL)

    2017-12-05

    Dec 5, 2017 ... 2017 Nigerian Journal of Clinical Practice | Published by Wolters Kluwer ‑ Medknow. Objectives: The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch ..... adhesion of a glass ionomer cement to dentin.

  15. Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser ...

    African Journals Online (AJOL)

    Objectives: The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch dentin bonding adhesives. Materials and Methods: Sixty extracted human molars were flattened to obtain dentin surfaces. The samples were divided into ...

  16. Long-term result of out-patient neodymium-doped yttrium aluminium garnet laser photocoagulation surgery for patients with epistaxis.

    Science.gov (United States)

    Zhang, J; Qiu, R; Wei, C

    2016-01-01

    To evaluate the long-term efficacy of out-patient neodymium-doped yttrium aluminium garnet laser photocoagulation surgery for patients with epistaxis. A retrospective clinical study was conducted. A total of 217 consecutive patients who presented with acute or recurrent epistaxis received neodymium-doped yttrium aluminium garnet laser photocoagulation treatment in an out-patient setting. At three years, 94 per cent of acute epistaxis patients versus 88 per cent of recurrent epistaxis patients reported no bleeding. The outcome scores at 12 weeks and 3 years after treatment showed no significant differences between the 2 groups (p = 0.207 and p = 0.186). However, there was a significant difference in outcome scores at four weeks after treatment (p = 0.034). The median (and mean ± standard deviation) pain levels experienced during the laser operation (performed in an office setting) were 4.0 (3.75 ± 2.09) in the acute epistaxis group and 4.0 (3.83 ± 2.01) in the recurrent epistaxis group. Neither group had any complications. Neodymium-doped yttrium aluminium garnet laser photocoagulation is desirable in the treatment of both acute and recurrent epistaxis, and has long-lasting efficacy.

  17. High power single-frequency and frequency-doubled laser with active compensation for the thermal lens effect of terbium gallium garnet crystal.

    Science.gov (United States)

    Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi

    2016-05-01

    The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved.

  18. Efficacy of holmium. Yttrium-aluminium-garnet (Ho: YAG) laser therapy for arthroscopic synovectomy of rheumatoid arthritis

    International Nuclear Information System (INIS)

    Inoue, Yasuo; Inoue, Kazuhiko; Kanbe, Katsuaki

    2008-01-01

    To clarify the efficacy of holmium: yttrium-aluminium-garnet (Ho: YAG) laser therapy for arthroscopic synovectomy of rheumatoid arthritis (RA), we treated 13 shoulders of 11 RA patients of whom 1 was stage I, 7 stage II, 2 stage III, and 1 stage IV. The duration of RA is 4.6 years on average and the follow-up period is an average of 14 months. The Ho: YAG laser was set at 10 Watt (W) to treat the bone erosion areas so as to reach the deep zones of the pannus in order to resect the synovium. We compared C-reactive protein (CRP), Disease activity score (DAS) 28 and magnetic resonance image (MRI) findings before and after surgery. We cultured primary synovial cells to assay cytokine production of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α. Morphological examination was performed after treatment with the Ho: YAG laser at 0, 1, 5, 10, 15 and 20 W. We found villous synovium proliferation with vascularity in the rotator interval and supra spinatus tendon in the shoulder joints. In the subacromial bursa, yellow fat tissue and white fibrous soft tissue were detected in almost all shoulders. After synovectomy using the Ho: YAG laser, CRP decreased from an average of 3.6 to 0.8 and DAS28 also decreased from an average of 5.4 to 3.7 at 14 months after surgery. MRI showed decreased panni with synovium and did not precede joint destruction after 14 months in 10 shoulders out of 13 (77%). At 20 W of the Ho: YAG laser treatment, the synovial cells shrank as in apoptosis and the number of cells also decreased. Laser treatment also resulted in the following significant changes: TNF-α production increased at 1, 10, 15 and 20 W (compared with 0 W) but not dose dependently; IL-1β and IL-6 increased up to 10 W (compared with 0 W) but decreased at 15 and 20 W (compared with 10 W). In morphological examination, after treatment with the Ho: YAG laser at 15 W, the synovial cells expanded and the number of cells decreased. Therefore, Ho: YAG laser therapy is effective

  19. Cracking susceptibility of aluminum alloys during laser welding

    Directory of Open Access Journals (Sweden)

    Lara Abbaschian

    2003-06-01

    Full Text Available The influence of laser parameters in welding aluminum alloys was studied in order to reduce hot cracking. The extension of cracks at the welding surface was used as a cracking susceptibility (CS index. It has been shown that the CS changes with changing welding velocity for binary Al-Cu alloys. In general, the CS index increased until a maximum velocity and then dropped to zero, generating a typical lambda-curve. This curve is due to two different mechanisms: 1 the refinement of porosities with increasing velocity and 2 the changes in the liquid fraction due to decreasing microsegregation with increasing velocities.

  20. Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method

    Science.gov (United States)

    Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

    2013-12-01

    A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

  1. Efficacy and safety of Erbium-doped Yttrium Aluminium Garnet fractional resurfacing laser for treatment of facial acne scars

    Directory of Open Access Journals (Sweden)

    Balakrishnan Nirmal

    2013-01-01

    Full Text Available Background: Treatment of acne scars with ablative fractional laser resurfacing has given good improvement. But, data on Indian skin are limited. A study comparing qualitative, quantitative, and subjective assessments is also lacking. Aim: Our aim was to assess the improvement of facial acne scars with Erbium-doped Yttrium Aluminium Garnet (Er:YAG 2940 nm fractional laser resurfacing and its adverse effects in 25 patients at a tertiary care teaching hospital. Methods: All 25 patients received four treatment sessions with Er:YAG fractional laser at 1-month interval. The laser parameters were kept constant for each of the four sittings in all patients. Qualitative and quantitative assessments were done using Goodman and Barron grading. Subjective assessment in percentage of improvement was also documented 1 month after each session. Photographs were taken before each treatment session and 1 month after the final session. Two unbiased dermatologists performed independent clinical assessments by comparing the photographs. The kappa statistics was used to monitor the agreement between the dermatologists and patients. Results: Most patients (96% showed atleast fair improvement. Rolling and superficial box scars showed higher significant improvement when compared with ice pick and deep box scars. Patient′s satisfaction of improvement was higher when compared to physician′s observations. No serious adverse effects were noted with exacerbation of acne lesions forming the majority. Conclusion: Ablative fractional photothermolysis is both effective and safe treatment for atrophic acne scars in Indian skin.Precise evaluation of acne scar treatment can be done by taking consistent digital photographs.

  2. Laser Surface Treatment and Modification of Aluminum Alloy Matrix Composites

    Science.gov (United States)

    Abbass, Muna Khethier

    2018-02-01

    The present work aimed to study the laser surface treatment and modification of Al-4.0%Cu-1.0%Mg alloy matrix composite reinforced with 10%SiC particles produced by stir casting. The specimens of the base alloy and composite were irradiated with an Nd:YAG laser of 1000 mJ, 1064 nm and 3 Hz . Dry wear test using the pin-on -disc technique at different sliding times (5-30 min) at a constant applied load and sliding speed were performed before and after laser treatment. Micro hardness and wear resistance were increased for all samples after laser hardening treatment. The improvement of these properties is explained by microstructural homogenization and grain refinement of the laser treated surface. Modification and refinement of SiC particles and grain refinement in the microstructure of the aluminum alloy matrix (α-Al) were observed by optical and SEM micrographs. The highest increase in hardness was 21.4% and 26.2% for the base alloy and composite sample respectively.

  3. Directivity measurements in aluminum using a laser ultrasonics system

    International Nuclear Information System (INIS)

    Sakamoto, J M S; Pacheco, G M; Tittmann, B R; Baba, A

    2011-01-01

    A laser ultrasonics system was setup to measure the directivity (angular dependence pattern) of the amplitude of ultrasonic waves generated in aluminum samples. A pulsed Nd:YAG laser operating at 1064 nm optical wavelength, with typical pulse width (FWHM) of 8 ns, and energy per pulse of 450 mJ, was used to generate the ultrasound waves in the samples. The laser detection system was a Mach-Zehnder interferometer with typical noise-limited resolution of 0.25 nm (rms), frequency range from 50 kHz to 20 MHz, and measurement range from -75 nm/V to +75 nm/V. Two different optical spot sizes of the Nd:YAG laser were used to generate waves in the ablation regime: one was focused and the other was unfocused. Using the obtained data, the directivity graphics were drawn and compared with the theoretical curves, showing a good agreement. The experiments showed the directivity as a function of the optical spot size. For a point ultrasonic source (or focused optical spot), the directivity shows that the longitudinal waves present considerable amplitude in all directions. For a larger ultrasonic source (or an unfocused optical spot) the directivity shows that the longitudinal waves are generated with the higher amplitudes inside angles around ±10 0 .

  4. Industrial garnet

    Science.gov (United States)

    Olson, D.W.

    2013-01-01

    Garnet has been used as a gemstone since the Bronze Age. However, garnet’s angular fractures, relatively high hardness and specific gravity, chemical inertness and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

  5. Molten pool characterization of laser lap welded copper and aluminum

    Science.gov (United States)

    Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu, Jr.

    2013-12-01

    A 3D finite volume simulation model for laser welding of a Cu-Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu-Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint.

  6. Molten pool characterization of laser lap welded copper and aluminum

    International Nuclear Information System (INIS)

    Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu Jr

    2013-01-01

    A 3D finite volume simulation model for laser welding of a Cu–Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu–Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint. (paper)

  7. Random laser action in stoichiometric Nd3Ga5O12 garnet crystal powder

    International Nuclear Information System (INIS)

    Iparraguirre, I; Azkargorta, J; Barredo-Zuriarrain, M; Balda, R; Fernández, J; Kamada, K; Yoshikawa, A; Rodríguez-Mendoza, U R; Lavín, V

    2016-01-01

    This work explores the room temperature infrared random laser (RL) performance of Nd 3+ ions in a new stoichiometric Nd 3 Ga 5 O 12 crystal powder. The time-resolved measurements show that the RL pulse is able to follow the subnanosecond oscillations of the pump pulse profile. The pump threshold energy and the absolute stimulated emission energy have been measured using a method developed by the authors. The laser slope efficiency is the highest compared to other Nd 3+ stoichiometric RL crystals. (letter)

  8. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    impurities, in the development of solid state laser crystals. Doping, dependent on the particular ion and crystal structure, may be as high as 100 at. % (complete substitution of yttrium ion with the rare earth ion). These materials have high melting points, 1940 C for YAG (Yttrium Aluminum Garnet), and low emissivity in the near infrared making them excellent candidates for a thin film selective emitter. As previously stated, the spectral emittance of a rare earth emitter is characterized by one or more well defined emission bands. Outside the emission band the emittance(absorptance) is much lower. Therefore, it is expected that emission outside the band for a thin film selective emitter will be dominated by the emitter substrate. For an efficient emitter (power in the emission band/total emitted power) the substrate must have low emittance, epsilon(sub S). This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium(Ho) and erbium (Er) doped YAG thin film selective emitters at (1500 K), and compares those results with the theoretical spectral emittance.

  9. Harmonic technology versus neodymium-doped yttrium aluminium garnet laser and electrocautery for lung metastasectomy: an experimental study.

    Science.gov (United States)

    Fiorelli, Alfonso; Accardo, Marina; Carelli, Emanuele; Del Prete, Assunta; Messina, Gaetana; Reginelli, Alfonso; Berritto, Daniela; Papale, Ferdinando; Armenia, Emilia; Chiodini, Paolo; Grassi, Roberto; Santini, Mario

    2016-07-01

    We compared the efficacy of non-anatomical lung resections with that of three other techniques: monopolar electrocautery; neodymium-doped yttrium aluminium garnet laser and harmonic technology. We hypothesized that the thermal damage with harmonic technology could be reduced because of the lower temperatures generated by harmonic technology compared with that of other devices. Initial studies were performed in 13 isolated pig lungs for each group. A 1.5-cm capsule was inserted within the lung to mimic a tumour and a total of 25 non-anatomical resections were performed with each device. The damage of the resected lung surface and of the tumour border were evaluated according to the colour (ranging from 0-pink colour to 4-black colour), histological (ranging from Score 0-no changes to Score 3-presence of necrotic tissue) and radiological (ranging from Score 0-isointense T2 signal at magnetic resonance imaging to Score 3-hyperintense T2 signal) criteria. A total of seven non-anatomical resections with harmonic technology were also performed in two live pigs to assess if ex vivo results could be reproducible in live pigs with particular attention to haemostatic and air-tightness properties. In the ex vivo lung, there was a statistical significant difference between depth of thermal damage (P laser (0.9 [0.6-0.9]) and harmonic (0.4 [0.3-0.5]) groups. Electrocautery had a higher depth of thermal damage compared with that of the laser (P = 0.01) and harmonic groups (P = 0.0005). The harmonic group had a less depth of thermal damage than that of the laser group (P = 0.01). Also, histological damages of tumour borders (P technology. Our experimental data support the resections performed with the use of harmonic technology. The lack of severe tissue alterations could favour healing of parenchyma, assure air tightness and preserve functional lung parenchyma. However, randomized controlled studies are needed in an in vivo model to corroborate our findings. © The Author 2016

  10. Zero ischemia laparoscopic partial thulium laser nephrectomy.

    LENUS (Irish Health Repository)

    Thomas, Arun Z

    2013-11-01

    Laser technology presents a promising alternative to achieve tumor excision and renal hemostasis with or without hilar occlusion, yet its use in partial nephrectomy has not been significantly evaluated. We prospectively evaluated the thulium:yttrium-aluminum-garnet laser in laparoscopic partial nephrectomy (LPN) in our institution over a 1-year period.

  11. Cladding For Transversely-Pumped Laser Rod

    Science.gov (United States)

    Byer, Robert L.; Fan, Tso Yee

    1989-01-01

    Combination of suitable dimensioning and cladding of neodymium:yttrium aluminum garnet of similar solid-state laser provides for more efficient utilization of transversely-incident pump light from diode lasers. New design overcomes some of limitations of longitudinal- and older transverse-pumping concepts and promotes operation at higher output powers in TEM00 mode.

  12. Reassembling Solid Materials by Femtosecond Laser Ablation: Case of Aluminum Nitride

    Science.gov (United States)

    Kobayashi, Tohru; Matsuo, Yukari

    2013-06-01

    Through atomization and ionization, we could completely alter the composition of a nonconductive material, aluminum nitride, by femtosecond laser ablation. Preferential production of pure aluminum cluster cations Aln+ (n≤32) reflects not only their higher energetic stability compared with mixed clusters AlnNm+ but also completion of thermal relaxation in ablation plasma. Observation of metastable dissociation of Aln+ indicates that cluster cations have still enough internal energy for dissociation to occur, although the process is much slower than the cluster formation. Almost no cluster formation has been observed after nanosecond laser ablation of aluminum nitride, which highlights the distinct nature of ablation plasma produced by femtosecond laser ablation.

  13. Industrial garnet

    Science.gov (United States)

    Olson, D.W.

    2007-01-01

    World production of industrial garnet was about 326 kt in 2006, with the U.S. producing about 11 percent of this total. U.S. consumption, imports, and exports were estimated at 74.3 kt, 52.3 kt, and 13.2 kt, respectively. The most important exporters are Australia, China, and India. Although demand is expected to rise over the next 5 years, prices are expected to remain low in the short term.

  14. Histologic effects of resurfacing lasers.

    Science.gov (United States)

    Freedman, Joshua R; Greene, Ryan M; Green, Jeremy B

    2014-02-01

    By utilizing resurfacing lasers, physicians can significantly improve the appearance of sun-damaged skin, scars, and more. The carbon dioxide and erbium:yttrium-aluminum-garnet lasers were the first ablative resurfacing lasers to offer impressive results although these earlier treatments were associated with significant downtime. Later, nonablative resurfacing lasers such as the neodymium:yttrium-aluminum-garnet laser proved effective, after a series of treatments with less downtime, but with more modest results. The theory of fractional photothermolysis has revolutionized resurfacing laser technology by increasing the safety profile of the devices while delivering clinical efficacy. A review of the histologic and molecular consequences of the resurfacing laser-tissue interaction allows for a better understanding of the devices and their clinical effects. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  15. Employment of Some Parameters to Enhance Laser-Drilling of Aluminum

    Directory of Open Access Journals (Sweden)

    Oday A. Hamadi

    2005-06-01

    Full Text Available In this work, some parameters affecting drilling of aluminum samples by a pulsed Nd:YAG laser were studied. These parameters are multi-pulses irradiation, controlling sample temperature, low-pressure ambient and application of electric field on the sample. Results presented in this work explained that these parameters can enhance drilling process throughout increasing hole depth in aluminum samples at the same laser energy used for irradiation.

  16. Aluminum and gallium substitution in yttrium and lutetium aluminum−gallium garnets: investigation by single-crystal NMR and TSL methods

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Zorenko, Y.; Gorbenko, V.; Iskalieva, A.; Zagorodniy, Y.; Sidletskiy, O.; Bilski, P.; Twardak, A.; Nikl, Martin

    2016-01-01

    Roč. 120, č. 42 (2016), s. 24400-24408 ISSN 1932-7447 R&D Projects: GA ČR GA16-15569S Institutional support: RVO:68378271 Keywords : garnets * Ga and Al site occupation * nuclear magnetic resonance * thermoluminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.536, year: 2016

  17. Pore formation during C.W.Nd: YAG laser welding of aluminum alloys for automotive applications

    International Nuclear Information System (INIS)

    Pastor, M.; Zhao, H.; DebRoy, T.

    2000-01-01

    Pore formation is an important concern in laser welding of automotive aluminum alloys. This paper investigates the influence of the laser beam defocusing on pore formation during continuous wave Nd:YAG laser welding of aluminum automotive alloys 5182 and 5754. It was found that the instability of the keyhole during welding was a dominant cause of pore formation while hydrogen rejection played an insignificant role. The defocusing of the laser beam greatly affected the stability of the keyhole. Finally, the mechanism of the collapse of the keyhole and pore formation is proposed. (Author) 45 refs

  18. Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications.

    Science.gov (United States)

    Verma, Mahesh; Kumari, Pooja; Gupta, Rekha; Gill, Shubhra; Gupta, Ankur

    2015-01-01

    Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique. Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3-0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine. The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer. Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength. Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

  19. Best laser for prostatectomy in the year 2013

    OpenAIRE

    Pankaj N Maheshwari; Nitin Joshi; Reeta P Maheshwari

    2013-01-01

    Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer's prostatectomy. Green light laser has a short learning curve, is nearly blo...

  20. CO{sub 2} laser coating of nanodiamond on aluminum using an annular beam

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Rodger; Molian, Pal, E-mail: molian@iastate.edu

    2014-01-01

    Laser coating of nanodiamond (ND) on aluminum alloy A319 substrate was investigated using a diffraction-free ring beam. A 1000 W continuous wave CO{sub 2} laser in the ring beam configuration heated the 25–35 μm thick electrostatically sprayed ND powder layers on aluminum surface, melted a very thin layer (10 μm) of aluminum in a controlled fashion and caused phase transition of ND to form 50–60 μm thick ND/diamond-like carbon (DLC) coating. Significant improvements in friction, wear resistance and surface finish were observed in the ring beam method over the traditional Gaussian beam method suggesting that these thick (50–60 μm) ND/DLC laser coatings can outperform the currently used thin (<4 μm) chemically vapor deposited DLC coatings for aluminum parts in automobiles.

  1. CO2 laser coating of nanodiamond on aluminum using an annular beam

    International Nuclear Information System (INIS)

    Blum, Rodger; Molian, Pal

    2014-01-01

    Laser coating of nanodiamond (ND) on aluminum alloy A319 substrate was investigated using a diffraction-free ring beam. A 1000 W continuous wave CO 2 laser in the ring beam configuration heated the 25–35 μm thick electrostatically sprayed ND powder layers on aluminum surface, melted a very thin layer (10 μm) of aluminum in a controlled fashion and caused phase transition of ND to form 50–60 μm thick ND/diamond-like carbon (DLC) coating. Significant improvements in friction, wear resistance and surface finish were observed in the ring beam method over the traditional Gaussian beam method suggesting that these thick (50–60 μm) ND/DLC laser coatings can outperform the currently used thin (<4 μm) chemically vapor deposited DLC coatings for aluminum parts in automobiles.

  2. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...

  3. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...... of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...

  4. Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

    Science.gov (United States)

    Malikov, A. G.; Orishich, A. M.

    2017-01-01

    The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

  5. Enhancing the Ductility of Laser-Welded Copper-Aluminum Connections by using Adapted Filler Materials

    Science.gov (United States)

    Weigl, M.; Albert, F.; Schmidt, M.

    Laser micro welding of direct copper-aluminum connections typically leads to the formation of intermetallic phases and an embrittlement of the metal joints. By means of adapted filler materials it is possible to reduce the brittle phases and thereby enhance the ductility of these dissimilar connections. As the element silicon features quite a well compatibility with copper and aluminum, filler materials based on Al-Si and Cu-Si alloys are used in the current research studies. In contrast to direct Cu-Al welds, the aluminum filler alloy AlSi12 effectuates a more uniform element mixture and a significantly enhanced ductility.

  6. Room-temperature picosecond high-order stimulated Raman scattering in laser garnet crystal hosts Gd3Ga5O12, Gd3Sc2Ga3O12, and Ca3(Nb,Ga)2Ga3O12

    International Nuclear Information System (INIS)

    Kaminskii, Alexandr A; Eichler, H J; Findeisen, J; Ueda, Ken-ichi; Fernandez, J; Balda, R

    1998-01-01

    High-order Stokes and anti-Stokes generation in the visible and near-infrared in cubic laser crystal hosts Gd 3 Ga 5 O 12 , Gd 3 Sc 2 Ga 3 O 12 , and Ca 3 (Nb,Ga) 2 Ga 3 O 12 was observed for the first time. All scattering-laser components were identified and attributed to the SRS-active vibration modes of these garnet crystals. (letters to the editor)

  7. Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping

    Science.gov (United States)

    Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

    1991-01-01

    Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

  8. Enabling lightweight designs by a new laser based approach for joining aluminum to steel

    Science.gov (United States)

    Brockmann, Rüdiger; Kaufmann, Sebastian; Kirchhoff, Marc; Candel-Ruiz, Antonio; Müllerschön, Oliver; Havrilla, David

    2015-03-01

    As sustainability is an essential requirement, lightweight design becomes more and more important, especially for mobility. Reduced weight ensures more efficient vehicles and enables better environmental impact. Besides the design, new materials and material combinations are one major trend to achieve the required weight savings. The use of Carbon Fiber Reinforced Plastics (abbr. CFRP) is widely discussed, but so far high volume applications are rarely to be found. This is mainly due to the fact that parts made of CFRP are much more expensive than conventional parts. Furthermore, the proper technologies for high volume production are not yet ready. Another material with a large potential for lightweight design is aluminum. In comparison to CFRP, aluminum alloys are generally more affordable. As aluminum is a metallic material, production technologies for high volume standard cutting or joining applications are already developed. In addition, bending and deep-drawing can be applied. In automotive engineering, hybrid structures such as combining high-strength steels with lightweight aluminum alloys retain significant weight reduction but also have an advantage over monolithic aluminum - enhanced behavior in case of crash. Therefore, since the use of steel for applications requiring high mechanical properties is unavoidable, methods for joining aluminum with steel parts have to be further developed. Former studies showed that the use of a laser beam can be a possibility to join aluminum to steel parts. In this sense, the laser welding process represents a major challenge, since both materials have different thermal expansion coefficients and properties related to the behavior in corrosive media. Additionally, brittle intermetallic phases are formed during welding. A promising approach to welding aluminum to steel is based on the use of Laser Metal Deposition (abbr. LMD) with deposit materials in the form of powders. Within the present work, the advantages of this

  9. Effects of laser shock peening on stress corrosion behavior of 7075 aluminum alloy laser welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.T., E-mail: jiasqq1225@126.com [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Chen, J.F.; Zhou, J.Y.; Ge, M.Z.; Lu, Y.L.; Li, X.L. [School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China)

    2015-10-28

    7075 aluminum alloy weldments were processed by an intensive process known as laser shock peening (LSP), meanwhile its stress corrosion behaviors were observed by scanning electron microscopy (SEM) and slow strain rate tensile (SSRT) tests. Results showed that the effect of LSP on corrosion behavior of the joint was fairly useful and obvious. With LSP, the elongation, time of fracture and static toughness after the SSRT test were improved by 11.13%, 20% and 100%, respectively. At the same time, the location of the fracture also changed. LSP led to a transition of the fracture type from transgranular to intergranular The reasons for these enhancements of the joint on corrosion behavior were caused by microstructure, residual stress, micro-hardness, and fracture appearance.

  10. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ming; Chen, Cong; Hu, Ming; Guo, Lianbo; Wang, Zemin, E-mail: zmwang@mail.hust.edu.cn; Zeng, Xiaoyan

    2015-01-30

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view.

  11. Thulium-yttrium-aluminium-garnet (Tm:YAG) laser treatment of penile cancer: oncological results, functional outcomes, and quality of life.

    Science.gov (United States)

    Musi, Gennaro; Russo, Andrea; Conti, Andrea; Mistretta, Francesco A; Di Trapani, Ettore; Luzzago, Stefano; Bianchi, Roberto; Renne, Giuseppe; Ramoni, Stefano; Ferro, Matteo; Matei, Deliu Victor; Cusini, Marco; Carmignani, Luca; de Cobelli, Ottavio

    2018-02-01

    To evaluate the oncological and functional outcomes of patients diagnosed with penile cancer undergoing conservative treatment through thulium-yttrium-aluminium-garnet (Tm:YAG) laser ablation. Twenty-six patients with a penile lesion underwent ablation with a RevoLix 200 W continuous-wave laser. The procedure was carried out with a pen-like laser hand piece, using a 360 μm laser fiber and 15-20 W of power. Median (IQR) follow-up time was 24 (15-30) months. Recurrence rate and post-operative sexual function were assessed. Median age at surgery was 61 years. Median (inter quartile range) size of the lesions was 15 [10-20] mm. Overall, 11 (47.8%) and 12 (52.2%) at the final pathology presented in situ and invasive squamous cell carcinoma (SCC), respectively. The final pathological stage was pTis, pT1a, pT2, and pT3 in 11 (47.8%), 7 (30.4%), 3 (13.0%), and 2 (8.7%) patients, respectively. Moreover, four (17.4%) patients had a recurrence of which three (13.0%) and one (4.3%) patients developed an invasive or in situ recurrence, respectively. After treatment 6 (26.1%) patients reported a conserved penile sensitivity, while 13 (56.5%) and 4 (17.4%) patients experienced a better or worse sensitivity after ablation, respectively. Post-treatment sexual activity was achieved within the first month after laser ablation in 82.6% of the patients. Early stage penile carcinomas can be effectively treated with an organ preservation strategy. Tm:YAG conservative laser treatment is easy, safe and offers good functional outcome, with a minor impact on patient's quality of life.

  12. Comparative study of the shear bond strength of composite resin bonded to enamel treated with acid etchant and erbium, chromium: Yttrium, scandium, gallium, garnet laser

    Directory of Open Access Journals (Sweden)

    Adel Sulaiman Alagl

    2016-01-01

    Full Text Available Aim: The purpose of this investigation is in vitro comparison of the shear bond strength (SBS of composite resin bonded to enamel pretreated with an acid etchant against enamel etched with erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr:YSGG laser. Materials and Methods: Sixty premolars were sectioned mesiodistally and these 120 specimens were separated into two groups of 60 each (Groups A and B. In Group A (buccal surfaces, enamel surface was etched using 37% phosphoric acid for 15 s. In Group B (lingual surfaces, enamel was laser-etched at 2W for 10 s by Er, Cr:YSGG laser operational at 2780 nm with pulse duration of 140 μs and a frequency of 20 Hz. After application of bonding agent on all test samples, a transparent plastic cylinder of 1.5 mm × 3 mm was loaded with composite and bonded by light curing for 20 s. All the samples were subjected to SBS analysis using Instron Universal testing machine. Failure modes were observed under light microscope and grouped as adhesive, cohesive, and mixed. Failure mode distributions were compared using the Chi-square test. Results: SBS values obtained for acid-etched enamel were in the range of 7.12–28.36 megapascals (MPa and for laser-etched enamel were in the range of 6.23–23.35 MPa. Mean SBS for acid-etched enamel was 15.77 ± 4.38 MPa, which was considerably greater (P < 0.01 than laser-etched enamel 11.24 ± 3.76 MPa. The Chi-square test revealed that the groups showed no statistically significant differences in bond failure modes. Conclusions: We concluded that the mean SBS of composite with acid etching is significantly higher as compared to Er, Cr: YSGG (operated at 2W for 10 s laser-etched enamel.

  13. Bimatoprost 0.03% versus brimonidine 0.2% in the prevention of intraocular pressure spike following neodymium:yttrium–aluminum–garnet laser posterior capsulotomy.

    Science.gov (United States)

    Artunay, Ozgur; Yuzbasioglu, Erdal; Unal, Mustafa; Rasier, Rifat; Sengul, Alper; Bahcecioglu, Halil

    2010-10-01

    The aim of this study was to compare the efficacy of bimatoprost 0.03% with brimonidine 0.2% in preventing intraocular pressure (IOP) elevations after neodymium:yttrium–aluminum–garnet (Nd:YAG) laser posterior capsulotomy. In this prospective, randomized, double-masked study, 195 eyes of 195 consecutive patients who had YAG laser capsulotomy for posterior capsule opacification were recruited. Eyes received either 1 drop of bimatoprost 0.03% (98 patients) or brimonidine 0.2% (97 patients) at 1h before laser surgery. A masked observer measured IOP by Goldmann applanation tonometry before treatment and after treatment at 1h, 3h, 24h, and 7 days. Inflammation was evaluated after surgery. Formation of cystoid macular edema was assessed by measuring the macular thickness before and after laser surgery. The average peak of postoperative IOP elevation was 2.2±3.9mm Hg in the bimatoprost 0.03% and 3.6±3.1mm Hg in the brimonidine 0.2% group. The difference was statistically significant (P<0.001). Postoperative IOP elevations of 10mm Hg or more occurred in 1 eye (1.56%) in the bimatoprost 0.03% group and 5 eyes (7.35%) in the brimonidine 0.2%. This difference was statistically significant (P<0.001). Macular edema and anterior chamber reaction were not observed related to bimatoprost. No clinically significant side effects were noted in either group. Our results indicate that prophylactic use of bimatoprost 0.03% is more effective than brimonidine 0.2% in preventing IOP elevation immediately after YAG laser capsulotomy. Bimatoprost 0.03% as a prostamide analog may provide new option for preventing IOP elevation after YAG laser capsulotomy.

  14. Effect of vapor plasma on the coupling of laser radiation with aluminum targets

    Energy Technology Data Exchange (ETDEWEB)

    Shui, V H; Kivel, B; Weyl, G M

    1978-12-01

    The effect of vapor plasma on thermal and impulse coupling of laser radiation with aluminum targets is studied to understand and explain experimental data showing anomalously high coupling to 10.6-micron laser radiation. Heating of vapor by inverse bremsstrahlung absorption of laser radiation, subsequent reradiation in the uv and deep uv by ionized species, and vapor layer growth are modeled. A computer code has been developed to solve the governing equations. Major conclusions include the following: (1) vapor plasma radiative transport can be an important mechanism for laser/target coupling, (2) aluminum vapor (density times thickness) approximately equal to 10 to the 17th power/sq cm (corresponding to about 0.01 micron of target material) can result in thermal coupling coefficients of 20% or more, and (3) too much vapor reduces the net flux at the target.

  15. High-strength laser welding of aluminum-lithium scandium-doped alloys

    Science.gov (United States)

    Malikov, A. G.; Ivanova, M. Yu.

    2016-11-01

    The work presents the experimental investigation of laser welding of an aluminum alloy (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of nano-structuring of the surface layer welded joint by cold plastic deformation on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys. The strength of the plastically deformed welded joint, aluminum alloys of the Al-Mg-Li and Al-Cu-Li systems reached 0.95 and 0.6 of the base alloy strength, respectively.

  16. Alkaline corrosion properties of laser-clad aluminum/titanium coatings

    DEFF Research Database (Denmark)

    Aggerbeck, Martin; Herbreteau, Alexis; Rombouts, Marleen

    2015-01-01

    Purpose - The purpose of this paper is to study the use of titanium as a protecting element for aluminum in alkaline conditions. Design/methodology/approach - Aluminum coatings containing up to 20 weight per cent Ti6Al4V were produced using laser cladding and were investigated using light optical...... microscope, scanning electron microscope - energy-dispersive X-ray spectroscopy and X-Ray Diffraction, together with alkaline exposure tests and potentiodynamic measurements at pH 13.5. Findings - Cladding resulted in a heterogeneous solidification microstructure containing an aluminum matrix...... with supersaturated titanium ( (1 weight per cent), Al3Ti intermetallics and large partially undissolved Ti6Al4V particles. Heat treatment lowered the titanium concentration in the aluminum matrix, changed the shape of the Al3Ti precipitates and increased the degree of dissolution of the Ti6Al4V particles. Corrosion...

  17. Digital laser printing of aluminum micro-structure on thermally sensitive substrates

    International Nuclear Information System (INIS)

    Zenou, Michael; Sa’ar, Amir; Kotler, Zvi

    2015-01-01

    Aluminum metal is of particular interest for use in printed electronics due to its low cost, high conductivity and low migration rate in electrically driven organic-based devices. However, the high reactivity of Al particles at the nano-scale is a major obstacle in preparing stable inks from this metal. We describe digital printing of aluminum micro-structures by laser-induced forward transfer in a sub-nanosecond pulse regime. We manage to jet highly stable molten aluminum micro-droplets with very low divergence, less than 2 mrad, from 500 nm thin metal donor layers. We analyze the micro-structural properties of the print geometry and their dependence on droplet volume, print gap and spreading. High quality printing of aluminum micro-patterns on plastic and paper is demonstrated. (paper)

  18. High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints

    Science.gov (United States)

    Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

    According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

  19. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    NARCIS (Netherlands)

    Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the

  20. Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

    Science.gov (United States)

    Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

    A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

  1. Controllable superhydrophobic aluminum surfaces with tunable adhesion fabricated by femtosecond laser

    Science.gov (United States)

    Song, Yuxin; Wang, Cong; Dong, Xinran; Yin, Kai; Zhang, Fan; Xie, Zheng; Chu, Dongkai; Duan, Ji'an

    2018-06-01

    In this study, a facile and detailed strategy to fabricate superhydrophobic aluminum surfaces with controllable adhesion by femtosecond laser ablation is presented. The influences of key femtosecond laser processing parameters including the scanning speed, laser power and interval on the wetting properties of the laser-ablated surfaces are investigated. It is demonstrated that the adhesion between water and superhydrophobic surface can be effectively tuned from extremely low adhesion to high adhesion by adjusting laser processing parameters. At the same time, the mechanism is discussed for the changes of the wetting behaviors of the laser-ablated surfaces. These superhydrophobic surfaces with tunable adhesion have many potential applications, such as self-cleaning surface, oil-water separation, anti-icing surface and liquid transportation.

  2. Effects on residual stresses of aluminum alloy LC4 by laser shock processing

    Science.gov (United States)

    Zhang, Yong-kang; Lu, Jin-zhong; Kong, De-jun; Yao, Hui-xue; Yang, Chao-jun

    2007-12-01

    The influences of processing parameters on laser-induced shock waves in metal components are discussed and analyzed. The effects of different parameters of laser shock processing (LSP) on residual stress of aerospace aluminum alloy LC4 were investigated. LSP was performed by using an Nd: glass phosphate laser with 23 ns pulse width and up to ~45 J pulse energy at power densities above GW/mm -2. Special attention is paid to the residual stresses from laser shock processing. Modification of microstructure, surface morphology by laser shock processing is also discussed. Results to date indicate that laser shock processing has great potential as a means of improving the mechanical performance of components.

  3. Effect of liquid properties on laser ablation of aluminum and titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Peixuan, E-mail: oypx12@mails.tsinghua.edu.cn [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Li, Peijie [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Leksina, E.G.; Michurin, S.V. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119992 (Russian Federation); He, Liangju [School of Aerospace, Tsinghua University, Beijing 100084 (China)

    2016-01-01

    Graphical abstract: - Highlights: • Porous surfaces are formed in Al alloy after wet ablation due to phase explosion. • A higher ablation rate is produced in glycerin than that in water and isopropanol. • Effect of liquid properties on mass-removal mechanisms was discussed. • Phase explosion and plasma-induced pressure contribute greatly to mass removal. • Density, heat conductivity and shock impendence of liquid affect ablation rates. - Abstract: In order to study the effect of liquid properties on laser ablation in liquids, aluminum 5A06 and titanium TB5 targets were irradiated by single-pulse infrared laser in isopropanol, distilled water, glycerin and as a comparison, in air, respectively. Craters induced by laser ablation were characterized using scanning electron and white-light interferometric microscopies. The results show that for liquid-mediated ablation, craters with porous surface structures were formed in aluminum target through phase explosion, while no micro-cavities were formed in titanium target owing to high critical temperature of titanium. In addition, ablation rates of aluminum and titanium targets vary with types of ambient media in accordance with such sequence: air < isopropanol < water < glycerin. Further, the influence of liquid properties on material-removal mechanisms for laser ablation in liquid is discussed. It is concluded that the density, thermal conductivity and acoustical impedance of liquid play a dominant role in laser ablation efficiency.

  4. Short-pulse neodymium:yttrium-aluminium garnet (Nd:YAG 1064nm) laser irradiation photobiomodulates mitochondria activity and cellular multiplication of Paramecium primaurelia (Protozoa).

    Science.gov (United States)

    Amaroli, Andrea; Benedicenti, Alberico; Ravera, Silvia; Parker, Steven; Selting, Wayne; Panfoli, Isabella; Benedicenti, Stefano

    2017-10-01

    Few studies exist to explore the potential photobiomodulation (PBM) effect of neodymium:yttrium-aluminium garnet (Nd:YAG) laser irradiation using a flat-top handpiece delivery system. In this study, we explored the photobiomodulation effect of that laser, on Paramecium primaurelia. The parameters for the different study groups were: 0.50W, 10Hz, 100msp, 30J/cm 2 ; 0.75W, 10Hz, 100msp, 45J/cm 2 ; 1.00W, 10Hz, 100msp, 60J/cm 2 ; 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 . Our results suggest that only the parameter 0.5W, 10Hz, 100msp, 30J/cm 2 positively photobiomodulates the Paramecium cells inducing an increment in oxygen consumption, endogenous ATP synthesis and fission rate rhythm. Applying the laser energy with parameters of 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 , induce adverse effect on the Paramecium cells, which protect themselves through the increase in Heat Shock Protein-70 (HSP70). The data presented in our work support our assumption that, when using appropriate parameters of irradiation, the 1064nm Nd:YAG laser with flat-top handpiece could be a valuable aid for effective clinical application of PBM. Copyright © 2017 Elsevier GmbH. All rights reserved.

  5. Applications of laser-induced breakdown spectroscopy in the aluminum electrolysis industry

    Science.gov (United States)

    Sun, Lanxiang; Yu, Haibin; Cong, Zhibo; Lu, Hui; Cao, Bin; Zeng, Peng; Dong, Wei; Li, Yang

    2018-04-01

    The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and corrosive conditions. Monitoring the molten aluminum and electrolyte components is very important for controlling the chemical reaction process. Due to the lack of fast methods to monitor the components, controlling aluminum reduction cells is difficult. In this work, laser-induced breakdown spectroscopy (LIBS) was applied to aluminum electrolysis. A new method for calculating the molecular ratio, which is an important control parameter that represents the acidity of the electrolyte, was proposed. Experiments were first performed on solid electrolyte samples to test the performance of the proposed method. Using this method, the average relative standard deviation (RSD) of the molecular ratio measurement was 0.39%, and the average root mean square error (RMSE) was 0.0236. These results prove that LIBS can accurately measure the molecular ratio. Then, in situ measurements of the molten aluminum and electrolyte were performed in industrial aluminum induction cells using the developed LIBS equipment. The spectra of the molten electrolyte were successfully obtained and were consistent with the spectra of the solid electrolyte.

  6. Laser-Ultrasonic Measurement of Elastic Properties of Anodized Aluminum Coatings

    Science.gov (United States)

    Singer, F.

    Anodized aluminum oxide plays a great role in many industrial applications, e.g. in order to achieve greater wear resistance. Since the hardness of the anodized films strongly depends on its processing parameters, it is important to characterize the influence of the processing parameters on the film properties. In this work the elastic material parameters of anodized aluminum were investigated using a laser-based ultrasound system. The anodized films were characterized analyzing the dispersion of Rayleigh waves with a one-layer model. It was shown that anodizing time and temperature strongly influence Rayleigh wave propagation.

  7. Effect of adding aluminum ion on the structural, optical, electrical and magnetic properties of terbium doped yttrium iron garnet nanoparticles films prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Aldbea, Ftema W.; Ibrahim, N.B., E-mail: baayah@ukm.edu.my; Yahya, M.

    2014-12-01

    Highlights: • The conductivity of YIG films increased with increasing of Al content. • The saturation magnetization at room temperature decreased with increasing Al{sup 3+} content. • Al{sup 3+} substituted Tb-YIG films has been prepared by a sol-gel method. - Abstract: Tb{sub 0.8}Y{sub 2.2}Al{sub y}Fe{sub 5−y}O{sub 12} nanoparticle films with y = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by a sol–gel method for potential use as a magnetic sensor and in magneto-optical applications. The films were deposited onto quartz substrate, followed by annealing at 900 °C in air for 2 h. X-ray diffractometry results confirmed the formation of a pure garnet structure. The lattice parameter decreased with increasing Al{sup 3+} content due to the substitution of Al{sup 3+} ions with the larger Fe{sup 3+} ions. The grain size of the films decreased up to y = 0.6. This variation is discussed based on the stress on the grain surface. The films observed to be transparent between 76 and 92% in the visible and infrared regions. The films demonstrated a strong absorption of 10{sup 4} cm{sup −1} caused by the charge transfer transition in the UV region. The absorption edge shifts to lower wavelengths at higher Al contents of 0.8 and 1 due to electronic transitions. The conductivity of films increased with increasing of Al content due to the increasing in free carrier concentration. The saturation magnetization at room temperature decreased with increasing Al{sup 3+} content, whereas the coercivity increased markedly at y = 0.6.

  8. Calibration curves for commercial copper and aluminum alloys using handheld laser-induced breakdown spectroscopy

    Science.gov (United States)

    Bennett, B. N.; Martin, M. Z.; Leonard, D. N.; Garlea, E.

    2018-03-01

    Handheld laser-induced breakdown spectroscopy (HH LIBS) was used to study the elemental composition of four copper alloys and four aluminum alloys to produce calibration curves. The HH LIBS instrument used is a SciAps Z-500, commercially available, that contains a class-1 solid-state laser with an output wavelength of 1532 nm, laser energy of 5 mJ/pulse, and a pulse duration of 5 ns. Test samples were solid specimens comprising copper and aluminum alloys and data were collected from the samples' surface at three different locations, employing a 12-point-grid pattern for each data set. All three data sets of the spectra were averaged, and the intensity, corrected by subtraction of background, was used to produce the elemental calibration curves. Calibration curves are presented for the matrix elements, copper and aluminum, as well as several minor elements. The surface damage produced by the laser was examined by microscopy. The alloys were tested in air and in a glovebox to evaluate the instrument's ability to identify the constituents within materials under different environmental conditions. The main objective of using this HH LIBS technology is to determine its capability to fingerprint the presence of certain elements related to subpercent level within materials in real time and in situ, as a starting point for undertaking future complex material characterization work.

  9. Porosity in fiber laser formation of 5A06 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yang Chun; Wang, Chun Ming; Hu, Xi Yuan; Wang, Jun; Yu, Sheng Fu [HUST, Wuhan (China)

    2010-05-15

    The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet's susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible

  10. Porosity in fiber laser formation of 5A06 aluminum alloy

    International Nuclear Information System (INIS)

    Yu, Yang Chun; Wang, Chun Ming; Hu, Xi Yuan; Wang, Jun; Yu, Sheng Fu

    2010-01-01

    The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet's susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible

  11. Picosecond Laser Pulse Interactions with Metallic and Semiconductor Surfaces.

    Science.gov (United States)

    1984-11-01

    thermometric determination of plasma relaxation is by far more sensitive than direct optical measurements. The solid line in Fig. 4 shows the calculated...passively mode-locked Nd:yttrium aluminum garnet in Si, several researchers have used high picosecond or fem- laser was used to produce single 30-ps, 1.06...these targets to an aluminum backing plate with a silver-epoxy conducting glue (Ablestik). The conductivity of the targets was high enough to make

  12. Single and double long pulse laser ablation of aluminum induced in air and water ambient

    International Nuclear Information System (INIS)

    Akbari Jafarabadi, Marzieh; Mahdieh, Mohammad Hossein

    2017-01-01

    Highlights: • Laser ablation of aluminum target by single and double pulse (∼ 5 ns delay) in ambient air and distilled water • Comparing with air, in ambient water, plasma confinement results in higher crater depth. • In comparison with single pulse laser ablation, the absorption of the laser pulse energy is higher for double pulse regime. • As a result of ablated material expansion, the crater depth is decreased if the target is placed at lower depth. - Abstract: In this paper, single pulse and double pulse laser ablation of an aluminum target in two interaction ambient was investigated experimentally. The interaction was performed by nanosecond Nd:YAG laser beam in air and four depths (i.e. 9, 13, 17, and 21 mm) of distilled water ambient. The irradiation was carried out in single and collinear double pulse configurations in both air and liquid ambient. Crater geometry (depth and diameter) was measured by an optical microscope. The results indicated that the crater geometry strongly depends on both single pulse and double pulse configurations and interaction ambient. In single pulse regime, the crater diameter is higher for all water depths compared to that of air. However, the crater depth, depend on water depth, is higher or lower than the crater depth in air. In double pulse laser ablation, there are greater values for both crater diameters and crater depths in the water.

  13. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  14. Ceramic Laser Materials

    Science.gov (United States)

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  15. Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment

    International Nuclear Information System (INIS)

    Saad, Rawad; L'Hermite, Daniel; Bousquet, Bruno

    2014-01-01

    The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 μs after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals. - Highlights: • Persistence of two Al I lines related to the 61,844 cm −1 energy level only under nitrogen atmosphere. • Collisional energy transfer effect exists between aluminum and nitrogen. • Observation of molecular band of AlN (under nitrogen) and AlO (under air) after a delay time of 1.5 µs. • 20% of oxygen in air is sufficient to annihilate both the collisional energy transfer effect and the AlN molecular formation

  16. Dissimilar material joining using laser (aluminum to steel using zinc-based filler wire)

    Science.gov (United States)

    Mathieu, Alexandre; Shabadi, Rajashekar; Deschamps, Alexis; Suery, Michel; Matteï, Simone; Grevey, Dominique; Cicala, Eugen

    2007-04-01

    Joining steel with aluminum involving the fusion of one or both materials is possible by laser beam welding technique. This paper describes a method, called laser braze welding, which is a suitable process to realize this structure. The main problem with thermal joining of steel/aluminum assembly with processes such as TIG or MIG is the formation of fragile intermetallic phases, which are detrimental to the mechanical performances of such joints. Braze welding permits a localized fusion of the materials resulting in a limitation on the growth of fragile phases. This article presents the results of a statistical approach for an overlap assembly configuration using a filler wire composed of 85% Zn and 15% Al. Tensile tests carried on these assemblies demonstrate a good performance of the joints. The fracture mechanisms of the joints are analyzed by a detailed characterization of the seams.

  17. Combined laser and atomic force microscope lithography on aluminum: Mask fabrication for nanoelectromechanical systems

    DEFF Research Database (Denmark)

    Berini, Abadal Gabriel; Boisen, Anja; Davis, Zachary James

    1999-01-01

    A direct-write laser system and an atomic force microscope (AFM) are combined to modify thin layers of aluminum on an oxidized silicon substrate, in order to fabricate conducting and robust etch masks with submicron features. These masks are very well suited for the production of nanoelectromecha......A direct-write laser system and an atomic force microscope (AFM) are combined to modify thin layers of aluminum on an oxidized silicon substrate, in order to fabricate conducting and robust etch masks with submicron features. These masks are very well suited for the production...... writing, and to perform submicron modifications by AFM oxidation. The mask fabrication for a nanoscale suspended resonator bridge is used to illustrate the advantages of this combined technique for NEMS. (C) 1999 American Institute of Physics. [S0003-6951(99)00221-1]....

  18. Cold spraying of aluminum bronze on profiled submillimeter cermet structures formed by laser cladding

    Science.gov (United States)

    Ryashin, N. S.; Malikov, A. G.; Shikalov, V. S.; Gulyaev, I. P.; Kuchumov, B. M.; Klinkov, S. V.; Kosarev, V. F.; Orishich, A. M.

    2017-10-01

    The paper presents results of the cold spraying of aluminum bronze coatings on substrates profiled with WC/Ni tracks obtained by laser cladding. Reinforcing cermet frames shaped as grids with varied mesh sizes were clad on stainless steel substrates using a CO2 laser machine "Siberia" (ITAM SB RAS, Russia). As a result, surfaces/substrates with heterogeneous shape, composition, and mechanical properties were obtained. Aluminum bronze coatings were deposited from 5lF-NS powder (Oerlikon Metco, Switzerland) on those substrates using cold spraying equipment (ITAM SB RAS). Data of profiling, microstructure diagnostics, EDS analysis, and mechanical tests of obtained composites is reported. Surface relief of the sprayed coatings dependence on substrate structure has been demonstrated.

  19. Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis.

    Science.gov (United States)

    Silva, M Z; Gouyon, R; Lepoutre, F

    2003-06-01

    Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The out of plane surface displacements produced by the propagating ultrasonic waves were detected with a heterodyne Mach-Zehnder interferometer. Time-frequency analysis of the signals using a continuous wavelet transform allowed the identification of the generated Lamb modes by comparison with the calculated dispersion curves. The presence of back surface corrosion was detected by noting the loss of the S(1) mode near its cutoff frequency. This method is applicable to fast scanning inspection techniques and it is particularly suited for early corrosion detection.

  20. Effects of Laser Energies on Wear and Tensile Properties of Biomimetic 7075 Aluminum Alloy

    Science.gov (United States)

    Yuan, Yuhuan; Zhang, Peng; Zhao, Guoping; Gao, Yang; Tao, Lixi; Chen, Heng; Zhang, Jianlong; Zhou, Hong

    2018-03-01

    Inspired by the non-smooth surface of certain animals, a biomimetic coupling unit with various sizes, microstructure, and hardness was prepared on the surface of 7075 aluminum alloy. Following experimental studies were conducted to investigate the wear and tensile properties with various laser energy inputs. The results demonstrated that the non-smooth surface with biomimetic coupling units had a positive effect on both the wear resistance and tensile property of 7075 aluminum alloy. In addition, the sample with the unit fabricated by the laser energy of 420.1 J/cm2 exhibited the most significant improvement on the wear and tensile properties owing to the minimum grain size and the highest microhardness. Also, the weight loss of the sample was one-third of the untreated one's, and the yield strength, the ultimate tensile strength, and the elongation improved by 20, 20, and 34% respectively. Moreover, the mechanisms of wear and tensile properties improvement were also analyzed.

  1. The microstructural mechanism for mechanical property of LY2 aluminum alloy after laser shock processing

    International Nuclear Information System (INIS)

    Luo, Kai-yu; Lu, Jin-zhong; Zhang, Ling-feng; Zhong, Jun-wei; Guan, Hai-bing; Qian, Xiao-ming

    2010-01-01

    This paper described nanoindentation techniques for measuring thin films mechanical properties, including elastic modulus and nano-hardness. The effects of laser shock processing (LSP) on elastic modulus and nano-hardness of the sample manufactured by LY2 aluminum alloy were experimentally investigated by nanoindentation techniques. Transmission electron microscope (TEM) observations of the microstructures in different regions after LSP are carried out. Experimental results showed that the values of nano-hardness and elastic modulus in the laser-shocked region were obviously increased by 58.13% and 61.74% compared to those in the non-shocked region, respectively. The influences of LSP on microstructure and grain size of LY2 aluminum alloy were discussed, and the enhancement mechanism of LSP on nano-hardness and elastic modulus was also addressed.

  2. Exploration of the fragmentation of laser shock-melted aluminum using x-ray backlighting

    Directory of Open Access Journals (Sweden)

    Lin Zhang

    2016-05-01

    Full Text Available The fragmentation of shock-melted metal material is an important scientific problem in shock physics and is suitable for experimentally investigating by the laser-driven x-ray backlighting technique. This letter reports on the exploration of laser shock-melted aluminum fragmentation by means of x-ray backlighting at the SGII high energy facility in China. High-quality and high-resolution radiographs with negligible motion blur were obtained and these images enabled analysis of the mass distribution of the fragmentation product.

  3. Elimination of Lubricants from Aluminum Cold Rolled Products Using Short Laser Pulses

    Directory of Open Access Journals (Sweden)

    Lima M.S.F.

    2002-01-01

    Full Text Available This work presents a new technique to remove the surface impurities from the aluminum cold-worked sheets. The method consists to concentrate a short-time high-power pulsed laser on the materials surface and scan it in order to cover a desired area. Incrustations ablation is obtained as long as the fluency and the peak power are high enough to produce vaporization of the contaminated layer without affecting the material surface properties. The present problem consists in eliminating a desiccated soap of about 1 g/m² from the surface of a 6016-class aluminum alloy sheet. The soap is originated from the rolling process. The present laser method is intended to replace water washing when the piece cannot be soaked, when drying is difficult due to the geometry, or when environmental restrictions apply. Best results were obtained when the pulse length was 100 ns and the average laser power was 95 W. In these conditions, the surface was completely cleaned and the aluminum alloy did not suffer any structural modification.

  4. High Strain Rate Response of 7055 Aluminum Alloy Subject to Square-spot Laser Shock Peening

    Science.gov (United States)

    Sun, Rujian; Zhu, Ying; Li, Liuhe; Guo, Wei; Peng, Peng

    2017-12-01

    The influences of laser pulse energy and impact time on high strain rate response of 7055 aluminum alloy subject to square-spot laser shock peening (SLSP) were investigate. Microstructural evolution was characterized by OM, SEM and TEM. Microhardness distribution and in-depth residual stress in 15 J with one and two impacts and 25 J with one and two impacts were analyzed. Results show that the original rolling structures were significantly refined due to laser shock induced recrystallization. High density of microdefects was generated, such as dislocation tangles, dislocation wall and stacking faults. Subgrains and nanograins were induced in the surface layer, resulting in grain refinement in the near surface layer after SLSP. Compressive residual stresses with maximum value of more than -200 MPa and affected depths of more than 1 mm can be generated after SLSP. Impact time has more effectiveness than laser pulse energy in increasing the magnitude of residual stress and achieving thicker hardening layer.

  5. Laser direct marking applied to rasterizing miniature Data Matrix Code on aluminum alloy

    Science.gov (United States)

    Li, Xia-Shuang; He, Wei-Ping; Lei, Lei; Wang, Jian; Guo, Gai-Fang; Zhang, Teng-Yun; Yue, Ting

    2016-03-01

    Precise miniaturization of 2D Data Matrix (DM) Codes on Aluminum alloy formed by raster mode laser direct part marking is demonstrated. The characteristic edge over-burn effects, which render vector mode laser direct part marking inadequate for producing precise and readable miniature codes, are minimized with raster mode laser marking. To obtain the control mechanism for the contrast and print growth of miniature DM code by raster laser marking process, the temperature field model of long pulse laser interaction with material is established. From the experimental results, laser average power and Q frequency have an important effect on the contrast and print growth of miniature DM code, and the threshold of laser average power and Q frequency for an identifiable miniature DM code are respectively 3.6 W and 110 kHz, which matches the model well within normal operating conditions. In addition, the empirical model of correlation occurring between laser marking parameters and module size is also obtained, and the optimal processing parameter values for an identifiable miniature DM code of different but certain data size are given. It is also found that an increase of the repeat scanning number effectively improves the surface finish of bore, the appearance consistency of modules, which has benefit to reading. The reading quality of miniature DM code is greatly improved using ultrasonic cleaning in water by avoiding the interference of color speckles surrounding modules.

  6. High level compressive residual stresses produced in aluminum alloys by laser shock processing

    International Nuclear Information System (INIS)

    Gomez-Rosas, G.; Rubio-Gonzalez, C.; Ocana, J.L; Molpeceres, C.; Porro, J.A.; Chi-Moreno, W.; Morales, M.

    2005-01-01

    Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm 2 in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm. Results using pulse densities of 2500 pulses/cm 2 in 6061-T6 aluminum samples and 5000 pulses/cm 2 in 2024 aluminum samples are presented. High level of compressive residual stresses are produced -1600 MPa for 6061-T6 Al alloy, and -1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products

  7. Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

    DEFF Research Database (Denmark)

    Bodea, M. A.; Sbarcea, G.; Naik, G. V.

    2013-01-01

    Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass...

  8. Effect of laser shot peening on precipitation hardened aluminum alloy 6061-T6 using low energy laser

    Science.gov (United States)

    Sathyajith, S.; Kalainathan, S.

    2012-03-01

    Mechanical properties of engineering material can be improved by introducing compressive residual stress on the material surface and refinement of their microstructure. Variety of mechanical process such as shot peening, water jet peening, ultrasonic peening, laser shot peening were developed in the last decades on this contrast. Among these, lasers shot peening emerged as a novel industrial treatment to improve the crack resistance of turbine blades and the stress corrosion cracking (SCC) of austenic stainless steel in power plants. In this study we successfully performed laser shot peening on precipitation hardened aluminum alloy 6061-T6 with low energy (300 mJ, 1064 nm) Nd:YAG laser using different pulse densities of 22 pulses/mm 2 and 32 pulses/mm 2. Residual stress evaluation based on X-ray diffraction sin 2 ψ method indicates a maximum of 190% percentage increase on surface compressive stress. Depth profile of micro-hardness shows the impact of laser generated shock wave up to 1.2 mm from the surface. Apart from that, the crystalline size and micro-strain on the laser shot peened surfaces have been investigated and compared with the unpeened surface using X-ray diffraction in conjunction with line broadening analysis through the Williamson-Hall plot.

  9. Influence of laser pulse frequency on the microstructure of aluminum nitride thin films synthesized by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, K., E-mail: krasa@issp.bas.bg [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Duta, L. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Szekeres, A. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Stan, G.E. [National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Magurele (Romania); Mihailescu, I.N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Anastasescu, M.; Stroescu, H.; Gartner, M. [Institute of Physical Chemistry, “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)

    2017-02-01

    Highlights: • Study of pulsed laser deposited AlN films at different laser pulse frequencies. • Higher laser pulse frequency promotes nanocrystallites formation at temperature 450 °C. • AFM and GIXRD detect randomly oriented wurtzite AlN structures. • Characterization of the nanocrystallites’ orientation by FTIR reflectance spectra. • Berreman effect is registered in p-polarised radiation at large incidence angles. - Abstract: Aluminum Nitride (AlN) thin films were synthesized on Si (100) wafers at 450 °C by pulsed laser deposition. A polycrystalline AlN target was multipulsed irradiated in a nitrogen ambient, at different laser pulse repetition rate. Grazing Incidence X-Ray Diffraction and Atomic Force Microscopy analyses evidenced nanocrystallites with a hexagonal lattice in the amorphous AlN matrix. The thickness and optical constants of the layers were determined by infrared spectroscopic ellipsometry. The optical properties were studied by Fourier Transform Infrared reflectance spectroscopy in polarised oblique incidence radiation. Berreman effect was observed around the longitudinal phonon modes of the crystalline AlN component. Angular dependence of the A{sub 1}LO mode frequency was analysed and connected to the orientation of the particles’ optical axis to the substrate surface normal. The role of the laser pulse frequency on the layers’ properties is discussed on this basis.

  10. Selection of an analytical line for determining lithium in aluminum alloys by laser induced breakdown spectrometry

    International Nuclear Information System (INIS)

    Lednev, V.N.; Yakovlev, A.V.; Labutin, T.A.; Popov, A.M.; Zorov, N.B.

    2007-01-01

    Possibilities for determining lithium in aluminum alloys by laser spark spectrometry are studied. The optimum conditions for registering the emission signal of lithium at which the effect of the continuous background radiation of the laser plasma attains a minimum are found. The possibility of determining lithium by laser spark spectrometry using the spectral line at 610 nm is studied for the first time. A comparison of the detection limits and sensitivities of determining lithium by emission its lines at 610 and 671 nm has indicated the advisability of using the line 610 nm for the studied alloys. The detection limit calculated using the 3σ test was found to be 230 ppm (610 nm) and 870 ppm (671 nm) [ru

  11. Radiation effects on the laser ablative shockwaves from aluminum under atmospheric conditions

    International Nuclear Information System (INIS)

    Sai Shiva, S.; Leela, C.H.; Prem Kiran, P.; Sijoy, C.D.; Chaturvedi, Shashank

    2015-01-01

    The evolution of laser ablative shockwaves (LASW) from Aluminum under atmospheric pressures is numerically modeled using a one-dimensional, three-temperature (electron, ion and thermal radiation temperatures), non-equilibrium, radiation hydrodynamic (RHD) model. The governing RHD equations in Lagrangian form are solved by using an implicit scheme. Similarly, the energy relaxation between the electrons and ions and the electrons and thermal radiation are determined implicitly. Apart from these, the energy equation takes into account the flux-limited electron thermal heat flux. The RHD equations are closed by using a two temperature QEOS model for the Al. The MULTI-fs code is modified to incorporate the nanosecond laser absorption model via the photoionization (PI) and the inverse bremsstrahlung (IB) processes. The spatio-temporal evolution of the laser ablative shockwaves generated by focusing a second harmonic (532 nm, 7ns) of Nd:YAG laser on to Aluminum target under atmospheric pressures in air is captured using a shadowgraphy technique. These measurements are made from 200 ns to 10 μs after the laser pulse with a temporal resolution of 1.5 ns. We report the details of the RHD model and compare the simulated and experimental results for input laser energies in the range of 25 - 175 mJ per pulse. The evolution of the plasma parameters like electron density, charge states and the shockwaves launched into the ambient atmosphere due to expanding plasma plume are compared. The role of thermal radiation on the evolution of LASW from Al is discussed. (author)

  12. Experimental Study of Laser - enhanced 5A03 Aluminum Alloy and Its Stress Corrosion Resistance

    Science.gov (United States)

    Wang, Guicheng; Chen, Jing; Pang, Tao

    2018-02-01

    Based on the study of improving the stress corrosion resistance of 5A03 aluminum alloy for ship, this paper mainly studied the tensile test, surface morphology and residual stress under laser shock, high temperature and stress corrosion. It is found that the residual compressive stress and the grain refinement on the surface of the material during the heat strengthening process increase the breaking strength of the sample in the stress corrosion environment. Appropriate high temperature maintenance helps to enhance the effect of deformation strengthening. In the 300°C environment insulation, due to recrystallization of the material, the performance decreased significantly. This study provides an experimental basis for effectively improving the stress corrosion resistance of 5A03 aluminum alloy.

  13. Experimental Study Of Polyformaldehyde Propellants Seeded With Micron-Scale Aluminum Powder For Laser Propulsion

    International Nuclear Information System (INIS)

    Li Long; Peng Jie; Hu Xiaojun; Zheng Hang; Tang Zhiping

    2010-01-01

    The propulsion performance of polyoxymethylene (POM) seeded with micron-scale aluminum (μAl) powder has been studied experimentally with CO 2 lasers. The results show that the momentum coupling coefficient (C m ) and specific impulse (I sp ) of POM seeded with μAl powder is almost the same as pure POM at lower power density ( 6 W/cm 2 ). At higher power density (>1·7xl0 6 W/cm 2 ), C m of POM seeded with μAl powder decreases significantly while I sp increases significantly. When this material is put into a cylindrical nozzle, the measured maximum C m and I sp can raise to 40.1 dyne/W and 1361 s, respectively. The energy usage ratio is over 100%, which indicates that the aluminum powder may react chemically with the air under the constraint condition. This conclusion was verified experimentally both in atmosphere and vacuum conditions.

  14. Experimental Investigation on Electric Current-Aided Laser Stake Welding of Aluminum Alloy T-Joints

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-11-01

    Full Text Available In the present study, aluminum alloy T-joints were welded using the laser stake-welding process. In order to improve the welding quality of the T-joints, an external electric current was used to aid the laser stake-welding process. The effects of the process parameters on the weld morphology, mechanical properties, and microstructure of the welded joints were analyzed and discussed in detail. The results indicate that the aided electric current should be no greater than a certain maximum value. Upon increasing the aided electric current, the weld width at the skin and stringer faying surface obviously increased, but there was an insignificant change in the penetration depth. Furthermore, the electric current and pressing force should be chosen to produce an expected weld width at the faying surface, whereas the laser power and welding speed should be primarily considered to obtain an optimal penetration depth. The tensile shear specimens failed across the faying surface or failed in the weld zone of the skin. The specimens that failed in the weld of the skin could resist a higher tensile shear load compared with specimens that failed across the faying surface. The microstructural observations and microhardness results demonstrated that the tensile shear load capacity of the aluminum alloy welded T-joint was mainly determined by the weld width at the faying surface.

  15. Characterization and Comparison of Aluminum, Silicon, and Carbon Laser Ablation Plumes

    Science.gov (United States)

    Iratcabal, Jeremy; Swanson, Kyle; Covington, Aaron

    2017-10-01

    Laser ablation of solid targets produces plasma plumes with rapidly evolving temperature and density gradients. These gradients can be measured using laser interferometric techniques that allow for the study of the plasma as the plume expands from the target surface and the temperature and density decrease. A systematic study of the temperature and density of aluminum, silicon, and carbon plasma plumes produced with a 2 TW/cm2 laser using spectroscopic, interferometric, fast imaging, and charge diagnostics will be presented. Carbon, aluminum, and silicon plumes are of interest because they are closely grouped on the periodic table but have very different material characteristics. Temporally and spatially resolved data was collected to characterize the evolution of the plasma in the plume. To probe the plasmas produced from these materials, optical spectroscopy was employed to identify and measure the temperature of the coexisting neutral and ionized atomic and molecular species. A Mach-Zehnder interferometer was employed to measure electron density. ICCD imaging and shadowgraphy were used to image the plume dynamics. A comparison of plasma evolution for each element will also be presented and will provide data to benchmark plasma codes. This work was supported by the University of Nevada, Reno, the U.S. DOE /NNSA Cooperative Agreement No. DE-NA0002075, and National Securities Technologies, LLC under Contract No. DE-AC52-06NA25946/Subcontract No. 165819.

  16. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

    Science.gov (United States)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

    2013-12-18

    Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  17. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    OpenAIRE

    Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

    2007-01-01

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the coating and the substrate, the macro-stresses were found to be compressive and to decrease in magnitude with increasing processing speed. The origin of the macro- and micro-stresses is discussed. T...

  18. Experiment and modeling: Ignition of aluminum particles with a carbon dioxide laser

    Science.gov (United States)

    Mohan, Salil

    Aluminum is a promising ingredient for high energy density compositions used in propulsion systems, explosives, and pyrotechnics. Aluminum powder fuel additives enable one to achieve higher combustion enthalpies and reaction temperatures. Therefore, to develop aluminum based novel and customized high density energetic materials, understanding of ignition and combustion kinetics of aluminum powders is required. In most practical systems, metal ignition and combustion occur in environments with rapidly changing temperatures and gas compositions. The kinetics of exothermic reactions in related energetic materials is commonly characterized by thermal analysis, where the heating rates are very low, on the order of 1--50 K/min. The extrapolation of the identified kinetics to the high heating rates is difficult and requires direct experimental verification. This difficulty led to development of new experimental approaches to directly characterize ignition kinetics for the heating rates in the range of 103--104 K/s. However, the practically interesting heating rates of 106 K/s range have not been achieved. This work is directed at development of an experimental technique and respective heat transfer model for studying ignition of aluminum and other micron-sized metallic particles at heating rates varied around 106 K/s. The experimental setup uses a focused CO2 laser as a heating source and a plate capacitor aerosolizer to feed the aluminum particles into the laser beam. The setup allows using different environment for particle aerosolization. The velocities of particles in the jet are in the range of 0.1 --0 3 m/s. For each selected jet velocity, the laser power is increased until the particles are observed to ignite. The ignition is detected optically using a digital camera and a photomultiplier. The ignition thresholds for spherical aluminum powder were measured at three different particle jet velocities, in air environment. A single particle heat transfer model was

  19. Theoretical analysis of deformation behavior of aluminum matrix composites in laser forming

    International Nuclear Information System (INIS)

    Liu, F.R.; Chan, K.C.; Tang, C.Y.

    2005-01-01

    In this paper, the deformation behavior of the SiC reinforced aluminum matrix composite in laser forming was investigated. A 2KW Nd:YAG laser was used to deform the composite at different laser powers, scanning speeds, numbers of irradiation passes and beam diameters. It was found that the bending angle increases with an increase in laser power, and a decrease in scanning speed and beam diameter. A relatively linear relationship between bending angle and number of irradiation passes was observed, and the effect of microstructural changes on the deformation behavior was discussed. An analytical model based on the Vollertsen's two-layer model was developed to predict the bending angle of the composite. The trends of the predictions are in good agreement with the experimental results. The effect of reinforcements on deformation behavior of the composite was further theoretically investigated. By modeling the changes of physical, thermal and mechanical properties including yield stress, elastic modulus, surface absorption coefficient and thermal conductivity of the material incorporated with SiC particles, the effect of reinforcement on laser bending angle was analyzed, and it was found that it would result in a larger bending angle. The significance of the findings will be discussed in the paper

  20. Stress corrosion cracking behavior of Nd:YAG laser-treated aluminum alloy 7075

    International Nuclear Information System (INIS)

    Yue, T.M.; Yan, L.J.; Chan, C.P.

    2006-01-01

    Nd-YAG laser surface treatment was conducted on 7075-T651 aluminum alloy with the aim of improving the stress corrosion cracking resistance of the alloy. Laser surface treatment was performed under two different gas environments, air and nitrogen. After the laser treatment, coarse constituent particles were removed and fine cellular/dendritic structures had formed. In addition, for the N 2 -treated specimen, an AlN phase was detected. The results of the stress corrosion test showed that after 30 days of immersion, the untreated specimen had been severely attacked by corrosion, with intergranular cracks having formed along the planar grain boundaries of the specimen. For the air-treated specimen, some relatively long stress corrosion cracks and a small number of relatively large corrosion pits were found. The cracks mainly followed the interdendritic boundaries; the fusion boundary was found to be acting as an arrestor to corrosion attacks. In contrast, only few short stress corrosion cracks appeared in the N 2 -treated specimen, indicating an improvement in corrosion initiation resistance. The superior corrosion resistance was attributed to the formation of the AlN phase in the surface of the laser-melted layer, which is an electrical insulator. The electrochemical impedance measurements taken during the stress corrosion test showed that the film resistance of the laser-treated specimens was always higher than that of the untreated specimen, with the N 2 -treated specimen showing the highest resistance

  1. Passivation of laser-treated nickel aluminum bronze as measured by electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Klassen, R.D.; Hyatt, C.V.; Roberge, P.R.

    2000-01-01

    Electrochemical impedance spectroscopy was used to assess the corrosion behavior of the weld zones and surface conditions of a laser-clad nickel aluminum bronze immersed in a 3.5% neutral saline solution. The zones and conditions examined included: (i) as-cast base material; (ii) laser-clad material with the high temperature oxide from welding intact; (iii) polished laser-clad material and (iv) specimens representative of just the as-deposited and reheated zones of the laser-clad surface. A pseudo steady-state level of passivation was reached in all the samples within 40 hours. The reheated zone passivated more slowly than the as-deposited region and both weld zones passivated more quickly than the base material. Electrochemical impedance data illustrated a transition during the passivation process of the polished specimens that is consistent with the development of a film layer that restricted mass transfer. The welding oxide from the laser treatment immediately behaved as a passivation film that was indistinguishable from that which eventually develops on polished specimens. (author)

  2. Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

    International Nuclear Information System (INIS)

    Baladi, Arash; Sarraf Mamoory, Rasoul

    2010-01-01

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.

  3. Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Baladi, Arash [Materials Engineering Department, Tarbiat Modares University, Jalal Al Ahmad, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Sarraf Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Materials Engineering Department, Tarbiat Modares University, Jalal Al Ahmad, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2010-10-01

    Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.

  4. Enhancement of low pressure cold sprayed copper coating adhesion by laser texturing on aluminum substrates

    Science.gov (United States)

    Knapp, Wolfgang; Gillet, Vincent; Courant, Bruno; Aubignat, Emilie; Costil, Sophie; Langlade, Cécile

    2017-02-01

    Surface pre-treatment is fundamental in thermal spraying processes to obtain a sufficient bonding strength between substrate and coating. Different pre-treatments can be used, mostly grit-blasting for current industrial applications. This study is focused on Cu-Al2O3 coatings obtained by Low Pressure Cold Spray on AW5083 aluminum alloy substrate. Bonding strength is measured by tensile adhesion test, while deposition efficiency is measured. Substrates are textured by laser, using a pattern of equally spaced grooves with almost constant diameter and variations of depth. Results show that bonding strength is improved up to +81% compared to non-treated substrate, while deposition efficiency remains constant. The study of the samples after rupture reveals a modification of the failure mode, from mixed failure to cohesive failure. A modification of crack propagation is also noticed, the shape of laser textured grooves induces a deviation of cracks inside the coating instead of following the interface between the layers.

  5. Characterization of an aluminum-filled polyamide powder for applications in selective laser sintering

    International Nuclear Information System (INIS)

    Mazzoli, Alida; Moriconi, Giacomo; Pauri, Marco Giuseppe

    2007-01-01

    Solid free-form fabrication (SFF) techniques use layer-based manufacturing to create physical objects directly from computer-generated models. Using an additive approach to manufacture shapes, SFF systems join liquid, powder or sheet materials. Selective laser sintering (SLS) is a SFF technique by which parts are built layer-by-layer offering the key advantage of the direct manufacturing of functional parts. In SLS, a laser beam is traced over the surface of a tightly compacted powder made of thermoplastic material. In this paper is characterized a new aluminum-filled polyamide powder developed for applications in SLS. This material is promising for many applications that require a metallic look of the part, good finishing properties, high stiffness and higher part quality

  6. A post-processing study on aluminum surface by fiber laser: Removing face milling patterns

    Science.gov (United States)

    Kayahan, Ersin

    2018-05-01

    The face milling process of the metal surface is a well-known machining process of using rotary cutters to remove material from a workpiece. Flat metal surfaces can be produced by a face milling process. However, in practice, visible, traced marks following the motion of points on the cutter's face are usually apparent. In this study, it was shown that milled patterns can be removed by means of 20 W fiber laser on the aluminum surface (AA7075). Experimental results also showed that roughened and hydrophobic surface can be produced with optimized laser parameters. It is a new approach to remove the patterns from the metal surface and can be explained through roughening by re-melting instead of ablation. The new method is a strong candidate to replace sandblasting the metal surface. It is also cheap and environmentally friendly.

  7. Influence of the laser parameters on the space and time characteristics of an aluminum laser-induced plasma

    International Nuclear Information System (INIS)

    Barthelemy, O.; Margot, J.; Chaker, M.; Sabsabi, M.; Vidal, F.; Johnston, T.W.; Laville, S.; Le Drogoff, B.

    2005-01-01

    In this work, an aluminum laser plasma produced in ambient air at atmospheric pressure by laser pulses at a fluence of 10 J/cm 2 is characterized by time- and space-resolved measurements of electron density and temperature. Varying the laser pulse duration from 6 ns to 80 fs and the laser wavelength from ultraviolet to infrared only slightly influences the plasma properties. The temperature exhibits a slight decrease both at the plasma edge and close to the target surface. The electron density is found to be spatially homogeneous in the ablation plume during the first microsecond. Finally, the plasma expansion is in good agreement with the Sedov's model during the first 500 ns and it becomes subsonic, with respect to the velocity of sound in air, typically 1 μs after the plasma creation. The physical interpretation of the experimental results is also discussed to the light of a one-dimensional fluid model which provides a good qualitative agreement with measurements

  8. Temporal follow-up of plasma parameter in an nuclear grade aluminum laser induced plasma at different laser energies by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Karki, Vijay; Singh, Manjeet; Sarkar, Arnab

    2015-07-01

    We report spectroscopic studies of laser induced plasma (LIP) produced by ns – 532 nm - Nd:YAG laser light pulses for different laser energies (35, 45 and 60 mJ) on an nuclear grade aluminum sample in air at atmospheric pressure. The temporal history of the plasma is obtained by recording the emission features at predetermined delays and at a fixed gate width (2.5 ì s). The temporal profiles of excitation temperature (T e ), ionization temperature (T ion ) and electron number density (N e ) were determined from Boltzmann plot, Saha-Boltzmann equation and Stark broadening method, respectively. T e , T ion and N e , shows a power law decay pattern with increasing acquisition time delay. T e has a positive correlation with laser energy, but the T ion and N e differ negligibly from one laser energy to another. Again the rate of decay of T e increases with increasing laser energy but that of T ion is much slower and independent of laser energy. The follow up of the local thermodynamic equilibrium (LTE) conditions were evaluated using both McWhirter criterion and T e /T ion ratio for different delays and different energies to determine the temporal range in which LTE is satisfied. Both the methods concluded very similar results except for very high energy and small delay conditions, where T e /T ion ratio deviates from unity indicating non-LTE condition. The relative transition probabilities of Al transition (3sp4s: 4 P 2/5 →3sp 2 : 4P 3/2,5/2 ) and (4s: 2 S 1/2 → 3p: 2 P 1/2,3/2 ) were estimated and are in excellent agreement with the Kurucz database. These investigations provide an insight to optimize various parameters during LIBS analysis of aluminum based matrices. (author)

  9. A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

    Science.gov (United States)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

    Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

  10. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    International Nuclear Information System (INIS)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A.; Shaji, S.

    2015-01-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al 2 O 3 and Fe 2 O 3 . • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe 2 O 3 , 20–40 nm) and aluminum oxide (Al 2 O 3 , 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 with a concentration of 5 and 7 wt% of Fe 2 O 3 presented the MgFe 2 O 4 spinel-type phase. With the addition of Al 2 O 3 nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 , there were the formations of MgAl 2 O 4 spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed

  11. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    International Nuclear Information System (INIS)

    Canteli, D.; Fernandez, S.; Molpeceres, C.; Torres, I.; Gandía, J.J.

    2012-01-01

    Highlights: ► A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. ► The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. ► A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 °C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  12. Non-contact sheet forming using lasers applied to a high strength aluminum alloy

    Directory of Open Access Journals (Sweden)

    Rafael Humberto Mota Siqueira

    2016-07-01

    Full Text Available Laser beam forming (LBF is a contactless mechanical process accomplished by the introduction of thermal stresses on the surface of a material using a laser in order to induce plastic deformation. In this work, LBF was performed on 1.6 mm thick sheets of a high strength aluminum alloy, AA6013-T4 class by using a defocused continuous Yb-fiber laser beam of 0.6 mm in diameter on the sheet top surface. The laser power and process speed were varied from 200 W to 2000 W and from 3 to 30 mm/s, respectively. For these experimental conditions, the bending angle of the sheet ranged from 0.1° to 2.5° per run. In the highest bending angle condition, 1000 W and 30 mm/s, the depth of remelted pool was 0.6 mm and the microstructure near the plate bottom surface remained unaltered. For the whole set of experimental conditions, the hardness remained constant at approximately 100 HV, which is similar to the base material. In order to verify the applicability of the method, some previously T-welded sheets were straightened. The method was efficient in correcting the distortion of the sheets with a bending angle up to 5°.

  13. Phonon transport in a curved aluminum thin film due to laser short pulse irradiation

    Science.gov (United States)

    Mansoor, Saad Bin; Yilbas, Bekir Sami

    2018-05-01

    Laser short-pulse heating of a curved aluminum thin film is investigated. The Boltzmann transport equation is incorporated to formulate the heating situation. A Gaussian laser intensity distribution is considered along the film arc and time exponentially decaying of pulse intensity is incorporated in the analysis. The governing equations of energy transport in the electron and lattice sub-systems are coupled through the electron-phonon coupling parameter. To quantify the phonon intensity distribution in the thin film, equivalent equilibrium temperature is introduced, which is associated with the average energy of all phonons around a local point when the phonon energies are redistributed adiabatically to an equilibrium state. It is found the numerical simulations that electron temperature follows similar trend to the spatial distribution of the laser pulse intensity at the film edge. Temporal variation of electron temperature does not follow the laser pulse intensity distribution. The rise of temperature in the electron sub-system is fast while it remains slow in the lattice sub-system.

  14. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Canteli, D., E-mail: david.canteli@ciemat.es [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Fernandez, S. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Molpeceres, C. [Centro Laser, Universidad Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Torres, I.; Gandia, J.J. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. Black-Right-Pointing-Pointer The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. Black-Right-Pointing-Pointer A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 Degree-Sign C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  15. An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

    International Nuclear Information System (INIS)

    Zhang, Jinping; Chen, Yuping; Hu, Mengning; Chen, Xianfeng

    2015-01-01

    In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes

  16. An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinping; Chen, Yuping, E-mail: ypchen@sjtu.edu.cn; Hu, Mengning; Chen, Xianfeng [State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-02-14

    In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes.

  17. High-efficiency cavity-dumped micro-chip Yb:YAG laser

    Science.gov (United States)

    Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

    2014-09-01

    High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

  18. A laser-based sizing/velocimetry technique to investigate the secondary atomization of aluminum gel propellants

    Science.gov (United States)

    Mueller, D. C.; Turns, S. R.

    1994-01-01

    A laser-based, forward-scatter diagnostic technique, employing a single laser sheet, has been developed to simultaneously measure the size and velocity of individual 10-150 micron droplets in a dilute polydisperse droplet stream (less than 1000 particles/cc) and to detect the presence of burning aluminum in these same droplets. Spectral emission from aluminum vapor in the 390-400 nm wavelength region is used as an indication of burning aluminum. The technique utilizes a 4-mm uniformly illuminated probe volume, eliminating trajectory-dependent particle sizing and size-dependent system detection bias. Particle sizing is based on a correlation of particle size with near-forward scattered light intensity. Calculations show average particle sizing variation to be within 3.5% over the expected range of refractive indices. Calibrations using a range of optical pinholes (10-100 micron) were used to verify the above sizing correlation.

  19. Effect of heat treatment on the properties of laser-beam welded rheo-cast F357 aluminum

    CSIR Research Space (South Africa)

    Theron, M

    2012-02-01

    Full Text Available Semi-solid metal rheo-cast F357 aluminum plates were joined by autogenous Nd:YAG laser welding and were welded in either the as-cast (F) condition, T4 temper or T6 temper condition. The weldability of this age-hardenable Al–7%Si–0.6%Mg casting alloy...

  20. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser

    DEFF Research Database (Denmark)

    Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.

    2010-01-01

    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...... efficiency of 76%. Our measurement showed that the pulse duration was 418 fs with the central wavelength of 1048 nm....

  1. Numerical and experimental investigation of laser induced plasma spectrum of aluminum in the presence of a noble gas

    International Nuclear Information System (INIS)

    Rezaei, Fatemeh; Tavassoli, Seyed Hassan

    2012-01-01

    Laser-induced plasma emission of an aluminum target in helium gas at 1 atm pressure is numerically and experimentally investigated. A laser pulse at wavelength of 266 nm and pulse duration of 10 ns has been considered. Laser ablation is calculated by a one dimensional model based on thermal evaporation mechanism. Spatial and temporal parameters of plasma expansion are determined by using hydrodynamic equations. Three kinds of plasma emission, including Bremsstrahlung, recombination and spectral emissions are considered for modeling the spectrum. Strong lines of aluminum and helium in wavelength interval of 200 to 450 nm are selected. Aluminum spectrum in UV range is depicted and compared with other spectral ranges. Temporal and spatial evolution of plasma emission up to 200 ns after the laser irradiation is studied. The effect of laser energy on the plasma spectrum is studied. An experimental set-up is arranged to compare numerical calculations with experimental results. Experimental and numerical results illustrate that helium line widths and peak intensities become narrower and weaker with time, respectively. Spatial distribution of spectrum shows that for closer distance to the sample surface, an intense continuous emission is observed, while at the farther distance, continuous emission decreases and spectral lines become sharper. A good coincidence is observed between experimental and numerical results. - Highlights: ► Aluminum plasma emission in helium is numerically and experimentally studied. ► Spectral, Bremsstrahlung and recombination emissions in spectrum are calculated. ► All strong lines of aluminum and helium are chosen for spectrum simulation. ► Line widths and peak intensities at later times become narrower and weaker. ► At specific optimum position, the maximum of signal peaks is acquired.

  2. Numerical and experimental investigation of laser induced plasma spectrum of aluminum in the presence of a noble gas

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, Fatemeh, E-mail: f_rezaei@sbu.ac.ir; Tavassoli, Seyed Hassan

    2012-12-01

    Laser-induced plasma emission of an aluminum target in helium gas at 1 atm pressure is numerically and experimentally investigated. A laser pulse at wavelength of 266 nm and pulse duration of 10 ns has been considered. Laser ablation is calculated by a one dimensional model based on thermal evaporation mechanism. Spatial and temporal parameters of plasma expansion are determined by using hydrodynamic equations. Three kinds of plasma emission, including Bremsstrahlung, recombination and spectral emissions are considered for modeling the spectrum. Strong lines of aluminum and helium in wavelength interval of 200 to 450 nm are selected. Aluminum spectrum in UV range is depicted and compared with other spectral ranges. Temporal and spatial evolution of plasma emission up to 200 ns after the laser irradiation is studied. The effect of laser energy on the plasma spectrum is studied. An experimental set-up is arranged to compare numerical calculations with experimental results. Experimental and numerical results illustrate that helium line widths and peak intensities become narrower and weaker with time, respectively. Spatial distribution of spectrum shows that for closer distance to the sample surface, an intense continuous emission is observed, while at the farther distance, continuous emission decreases and spectral lines become sharper. A good coincidence is observed between experimental and numerical results. - Highlights: Black-Right-Pointing-Pointer Aluminum plasma emission in helium is numerically and experimentally studied. Black-Right-Pointing-Pointer Spectral, Bremsstrahlung and recombination emissions in spectrum are calculated. Black-Right-Pointing-Pointer All strong lines of aluminum and helium are chosen for spectrum simulation. Black-Right-Pointing-Pointer Line widths and peak intensities at later times become narrower and weaker. Black-Right-Pointing-Pointer At specific optimum position, the maximum of signal peaks is acquired.

  3. Effect of Shielding Gas on the Properties of AW 5083 Aluminum Alloy Laser Weld Joints

    Science.gov (United States)

    Vyskoč, Maroš; Sahul, Miroslav; Sahul, Martin

    2018-04-01

    The paper deals with the evaluation of the shielding gas influence on the properties of AW 5083 aluminum alloy weld joints produced with disk laser. Butt weld joints were produced under different shielding gas types, namely Ar, He, Ar + 5 vol.% He, Ar + 30 vol.% He and without shielding weld pool. Light and electron microscopy, computed tomography, microhardness measurements and tensile testing were used for evaluation of weld joint properties. He-shielded weld joints were the narrowest ones. On the other hand, Ar-shielded weld joints exhibited largest weld width. The choice of shielding gas had significant influence on the porosity level of welds. The lowest porosity was observed in weld joint produced in Ar with the addition of 5 vol.% He shielding atmosphere (only 0.03%), while the highest level of porosity was detected in weld joint produced in pure He (0.24%). Except unshielded aluminum alloy weld joint, the lowest tensile strength was recorded in He-shielded weld joints. On the contrary, the highest average microhardness was measured in He-shielded weld joints.

  4. Application of slip-band visualization technique to tensile analysis of laser-welded aluminum alloy

    Science.gov (United States)

    Muchiar, -; Yoshida, Sanichiro J.; Widiastuti, Rini; Kusnowo, A.; Takahashi, Kunimitsu; Sato, Shunichi

    1997-03-01

    Recently we have developed a new optical interferometric technique capable of visualizing slip band occurring in a deforming solid-state object. In this work we applied this technique to a tensile analysis of laser-welded aluminum plate samples, and successfully revealed stress concentration that shows strong relationships with the tensile strength and the fracture mechanism. We believe that this method is a new, convenient way to analyze the deformation characteristics of welded objects and evaluate the quality of welding. The analysis has been made for several types of aluminum alloys under various welding conditions, and has shown the following general results. When the penetration is deep, a slip band starts appearing at the fusion zone in an early stage of the elastic region of the strain-stress curve and stays there till the sample fractures at that point. When the penetration is shallow, a slip band appears only after the yield point and moves vigorously over the whole surface of the sample till a late stage of plastic deformation when the slip band stays at the fusion zone where the sample eventually fractures. When the penetration depth is medium, some intermediate situation of the above two extreme cases is observed.

  5. Inclusion Detection in Aluminum Alloys Via Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Hudson, Shaymus W.; Craparo, Joseph; De Saro, Robert; Apelian, Diran

    2018-04-01

    Laser-induced breakdown spectroscopy (LIBS) has shown promise as a technique to quickly determine molten metal chemistry in real time. Because of its characteristics, LIBS could also be used as a technique to sense for unwanted inclusions and impurities. Simulated Al2O3 inclusions were added to molten aluminum via a metal-matrix composite. LIBS was performed in situ to determine whether particles could be detected. Outlier analysis on oxygen signal was performed on LIBS data and compared to oxide volume fraction measured through metallography. It was determined that LIBS could differentiate between melts with different amounts of inclusions by monitoring the fluctuations in signal for elements of interest. LIBS shows promise as an enabling tool for monitoring metal cleanliness.

  6. Effects of filling material and laser power on the formation of intermetallic compounds during laser-assisted friction stir butt welding of steel and aluminum alloys

    Science.gov (United States)

    Fei, Xinjiang; Jin, Xiangzhong; Peng, Nanxiang; Ye, Ying; Wu, Sigen; Dai, Houfu

    2016-11-01

    In this paper, two kinds of materials, Ni and Zn, are selected as filling material during laser-assisted friction stir butt welding of Q235 steel and 6061-T6 aluminum alloy, and their influences on the formation of intermetallic compounds on the steel/aluminum interface of the joints were first studied. SEM was used to analyze the profile of the intermetallic compound layer and the fractography of tensile fracture surfaces. In addition, EDS was applied to investigate the types of the intermetallic compounds. The results indicate that a thin iron-abundant intermetallic compound layer forms and ductile fracture mode occurs when Ni is added, but a thick aluminum-abundant intermetallic compound layer generates and brittle fracture mode occurs when Zn is added. So the tensile strength of the welds with Ni as filling material is greater than that with Zn as filling material. Besides, the effect of laser power on the formation of intermetallic compound layer when Ni is added was investigated. The preheated temperature field produced by laser beam in the cross section of workpiece was calculated, and the tensile strength of the joints at different laser powers was tested. Results show that only when suitable laser power is adopted, can suitable preheating temperature of the steel reach, then can thin intermetallic compound layer form and high tensile strength of the joints reach. Either excessive or insufficient laser power will reduce the tensile strength of the joints.

  7. Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel

    Science.gov (United States)

    Mohammadpour, Masoud; Yazdian, Nima; Yang, Guang; Wang, Hui-Ping; Carlson, Blair; Kovacevic, Radovan

    2018-01-01

    In this investigation, the joining of two types of galvanized steel and Al6022 aluminum alloy in a coach peel configuration was carried out using a laser welding-brazing process in dual-beam mode. The feasibility of this method to obtain a sound and uniform brazed bead with high surface quality at a high welding speed was investigated by employing AlSi12 as a consumable material. The effects of alloying elements on the thickness of intermetallic compound (IMC) produced at the interface of steel and aluminum, surface roughness, edge straightness and the tensile strength of the resultant joint were studied. The comprehensive study was conducted on the microstructure of joints by means of a scanning electron microscopy and EDS. Results showed that a dual-beam laser shape and high scanning speed could control the thickness of IMC as thin as 3 μm and alter the failure location from the steel-brazed interface toward the Al-brazed interface. The numerical simulation of thermal regime was conducted by the Finite Element Method (FEM), and simulation results were validated through comparative experimental data. FEM thermal modeling evidenced that the peak temperatures at the Al-steel interface were around the critical temperature range of 700-900 °C that is required for the highest growth rate of IMC. However, the time duration that the molten pool was placed inside this temperature range was less than 1 s, and this duration was too short for diffusion-control based IMC growth.

  8. Multi-stage pulsed laser deposition of aluminum nitride at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Duta, L. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Stan, G.E. [National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Magurele (Romania); Stroescu, H.; Gartner, M.; Anastasescu, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Fogarassy, Zs. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Konkoly Thege Miklos u. 29-33, H-1121 Budapest (Hungary); Mihailescu, N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Szekeres, A., E-mail: szekeres@issp.bas.bg [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Bakalova, S. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania)

    2016-06-30

    Highlights: • Multi-stage pulsed laser deposition of aluminum nitride at different temperatures. • 800 °C seed film boosts the next growth of crystalline structures at lower temperature. • Two-stage deposited AlN samples exhibit randomly oriented wurtzite structures. • Band gap energy values increase with deposition temperature. • Correlation was observed between single- and multi-stage AlN films. - Abstract: We report on multi-stage pulsed laser deposition of aluminum nitride (AlN) on Si (1 0 0) wafers, at different temperatures. The first stage of deposition was carried out at 800 °C, the optimum temperature for AlN crystallization. In the second stage, the deposition was conducted at lower temperatures (room temperature, 350 °C or 450 °C), in ambient Nitrogen, at 0.1 Pa. The synthesized structures were analyzed by grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy and spectroscopic ellipsometry (SE). GIXRD measurements indicated that the two-stage deposited AlN samples exhibited a randomly oriented wurtzite structure with nanosized crystallites. The peaks were shifted to larger angles, indicative for smaller inter-planar distances. Remarkably, TEM images demonstrated that the high-temperature AlN “seed” layers (800 °C) promoted the growth of poly-crystalline AlN structures at lower deposition temperatures. When increasing the deposition temperature, the surface roughness of the samples exhibited values in the range of 0.4–2.3 nm. SE analyses showed structures which yield band gap values within the range of 4.0–5.7 eV. A correlation between the results of single- and multi-stage AlN depositions was observed.

  9. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

  10. Fractional laser skin resurfacing.

    Science.gov (United States)

    Alexiades-Armenakas, Macrene R; Dover, Jeffrey S; Arndt, Kenneth A

    2012-11-01

    Laser skin resurfacing (LSR) has evolved over the past 2 decades from traditional ablative to fractional nonablative and fractional ablative resurfacing. Traditional ablative LSR was highly effective in reducing rhytides, photoaging, and acne scarring but was associated with significant side effects and complications. In contrast, nonablative LSR was very safe but failed to deliver consistent clinical improvement. Fractional LSR has achieved the middle ground; it combined the efficacy of traditional LSR with the safety of nonablative modalities. The first fractional laser was a nonablative erbium-doped yttrium aluminum garnet (Er:YAG) laser that produced microscopic columns of thermal injury in the epidermis and upper dermis. Heralding an entirely new concept of laser energy delivery, it delivered the laser beam in microarrays. It resulted in microscopic columns of treated tissue and intervening areas of untreated skin, which yielded rapid reepithelialization. Fractional delivery was quickly applied to ablative wavelengths such as carbon dioxide, Er:YAG, and yttrium scandium gallium garnet (2,790 nm), providing more significant clinical outcomes. Adjustable laser parameters, including power, pitch, dwell time, and spot density, allowed for precise determination of percent surface area, affected penetration depth, and clinical recovery time and efficacy. Fractional LSR has been a significant advance to the laser field, striking the balance between safety and efficacy.

  11. Laser-assisted ignition and combustion characteristics of consolidated aluminum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Saceleanu, Florin; Wen, John Z., E-mail: john.wen@uwaterloo.ca [University of Waterloo, Department of Mechanical and Mechatronics Engineering (Canada); Idir, Mahmoud; Chaumeix, Nabiha [Institut de Combustion, Aérothermique, Réactivité et Environnement, UPR3021 du CNRS-INSIS (France)

    2016-11-15

    Aluminum (Al) nanoparticles have drawn much attention due to their high energy density and tunable ignition properties. In comparison with their micronscale counterpart, Al nanoparticles possess large specific surface area and low apparent activation energy of combustion, which reduce ignition delay significantly. In this paper, ignition and subsequently burning of consolidated Al nanoparticle pellets are performed via a continuous wave (CW) argon laser in a closed spherical chamber filled with oxygen. Pellets are fabricated using two types of nanoparticle sizes of 40–60 and 60–80 nm, respectively. A photodiode is used to measure the ignition delay, while a digital camera captures the location of the flame front. It is found that for the 40–60-nm nanoparticle pellets, ignition delay reduces with increasing the oxygen pressure or using the higher laser power. Analysis of the flame propagation rate suggests that oxygen diffusion is an important mechanism during burning of these porous nanoparticle pellets. The combustion characteristics of the Al pellets are compared to a simplified model of the diffusion-controlled oxidation mechanism. While experimental measurements of pellets of 40–60 nm Al particles agree with the computed diffusion-limiting mechanism, a shifted behavior is observed from the pellets of 60–80 nm Al particles, largely due to the inhomogeneity of their porous structures.

  12. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Science.gov (United States)

    Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-01-01

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. PMID:29443912

  13. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting.

    Science.gov (United States)

    Koutny, Daniel; Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-02-14

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  14. Effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Rubio-Gonzalez, C.; Ocana, J.L.; Gomez-Rosas, G.; Molpeceres, C.; Paredes, M.; Banderas, A.; Porro, J.; Morales, M.

    2004-01-01

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 1.2 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto a water-immersed type aluminum samples. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the higher the pulse density the larger the zone size with compressive residual stress. Densities of 900, 1350 and 2500 pulses/cm 2 with infrared (1064 nm) radiation are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. Fatigue crack growth rate is compared in specimens with and without LSP process. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness in the 6061-T6 aluminum alloy

  15. Effect of an absorbent overlay on the residual stress field induced by laser shock processing on aluminum samples

    International Nuclear Information System (INIS)

    Rubio-Gonzalez, C.; Gomez-Rosas, G.; Ocana, J.L.; Molpeceres, C.; Banderas, A.; Porro, J.; Morales, M.

    2006-01-01

    Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm 2 with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy

  16. Laser treatment of cutaneous angiokeratomas: A systematic review.

    Science.gov (United States)

    Nguyen, Jannett; Chapman, Lance W; Korta, Dorota Z; Zachary, Christopher B

    2017-11-01

    Angiokeratomas can present therapeutic challenges, especially in cases of extensive lesions, where traditional surgical methods carry high risks of scarring and hemorrhage. Argon, pulsed dye (PDL), neodymium-doped yttrium aluminum garnet (Nd:YAG), copper vapor, potassium titanyl phosphate, carbon dioxide, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers have emerged as alternative options. To review the use and efficacy of lasers in treating angiokeratomas. A PubMed search identified randomized clinical trials, cohort studies, case series, and case reports involving laser treatment of cutaneous angiokeratomas. Twenty-five studies were included. Quality ratings were assigned using the Oxford Centre for Evidence-Based Medicine scheme. Several laser modalities are effective in treating multiple variants of angiokeratomas. Vascular lasers like PDL, Nd:YAG, and argon are the most studied and of these, PDL offers the safest side effect profile. Nd:YAG may be more effective for hyperkeratotic angiokeratomas. Combination treatment with multiple laser modalities has also demonstrated some success. Lasers are a promising treatment option for angiokeratomas, but current use is limited by the lack of treatment guidelines. There are limited high quality studies comparing laser treatments to each other and to non-laser options. Additional studies are needed to establish guidelines and to optimize laser parameters. © 2017 Wiley Periodicals, Inc.

  17. Weldability of Advanced High Strength Steels using Ytterbium:Yttrium Aluminium Garnet high power laser for Tailor-Welded Blank applications

    Science.gov (United States)

    Sharma, Rajashekhar Shivaram

    transverse direction were evaluated. Metallographic examinations determined that most of the fusion zone is martensitic with small regions of bainite and ferrite. High microhardness values of the order of 550--600 Hv were noted in most joints, which are attributed to high alloy content of the fusion zone as well as high rates of cooling typical of laser welds. During tensile, fatigue and formability tests, no fractures in the fusion or heat affected zones were observed. Geometric variability evaluations indicated that coatings such as aluminum (in the case of USIBOR) and galvanized zinc (TRIP780) can affect the variability of the weld zone and the surface roughness on the top of the weld. Excessive variability in the form of weld concavity in the weld zones can lead to fractures in the weld region, even though higher hardness can, to some extent, compensate for these surface irregularities. The 2-factor design of experiments further confirmed that coatings adversely affect the surface roughness on the top of the welds. Although thickness differentials alone do not make a significant impact on surface roughness, together with coatings, they can have an adverse effect on roughness. Tensile tests in the direction of rolling as well as in the transverse direction indicate that TRIP780 seems weaker in the direction of rolling when compared to transverse direction while mild steel is stronger in the direction of rolling. Weldability analyses revealed that the typical melting efficiency is on the order of 50--70% for full penetration welding. Formability tests showed that TR/MS joints fractured in a direction parallel to the weld line when tested with the loads perpendicular to the weld line. Tests have also confirmed that weld speed and power have no impact on the outcome of formability results. Overall, this work conclusively proves that high power Yb:YAG lasers can effectively join high strength materials such as DP980, TRIP780, USIBOR, as well as mild steel, for use in tailor

  18. Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

    International Nuclear Information System (INIS)

    Xu Jiang; Liu Wenjin; Kan Yide; Zhong Minlin

    2006-01-01

    In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB 2 and Ti 3 B 4 peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO 2 laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB 2 , Ti 3 B 4 , Al 3 Ti, Al 3 Fe and α-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB 2 and Ti 3 B 4 peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB 2 and Ti 3 B 4 peritectic improve wear resistance when compared with the as-received Al substrate

  19. Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xu Jiang [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)]. E-mail: xujiang73@sina.com.cn; Liu Wenjin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Kan Yide [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Zhong Minlin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)

    2006-07-01

    In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO{sub 2} laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB{sub 2}, Ti{sub 3}B{sub 4}, Al{sub 3}Ti, Al{sub 3}Fe and {alpha}-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic improve wear resistance when compared with the as-received Al substrate.

  20. Influence of scandium on the microstructure and strength properties of the welded joint at the laser welding of aluminum-lithium alloys

    Science.gov (United States)

    Malikov, A. G.; Golyshev, A. A.; Ivanova, M. Yu.

    2017-10-01

    Today, aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from lithium admixture. Various technologies of fusible welding of these alloys are being developed. Serious demands are imposed to the welded joints of aluminum alloys in respect to their strength characteristics. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint. The effect of scandium on the micro-and macro-structure has been studied as well as the strength characteristics of the welded joint. It has been found that scandium under in the laser welding process increases the welded joint elasticity for the system Al-Mg-Li, aluminum alloy 1420 by 20 %, and almost doubles the same for the system Al-Cu-Li, aluminum alloy 1441.

  1. Laser welding of aluminum alloy sheet test%铝合金薄板激光焊接试验

    Institute of Scientific and Technical Information of China (English)

    王中林; 杨晟; 石金发

    2011-01-01

    The purpse of Technology testing is to find a relatively economical and practical method of laser welding of aluminum alloy for the modem industrial assembly technology to provide new ideas to promote productivity improvement and cost reduction. Analyzed the characteristics of aluminum alloy laser welding technology, technical difficulties and Solutions, recording using 300W single - beam laser welding of aluminum alloy with the relevant parameters and tile welding effect, to build dual - beam laser welding test platform for high - power dual - beam and record the total about 500W into two beams of laser welding and related parameters during the test. By laser and argon arc welding test mixture. On the part of the welded samples were quantitatively analyzed. After analysis, made of aluminum alloy laser welding technology improvements.%工艺试验的目的是寻求相对经济实用的铝合金激光焊接方法,为现代工业装配生产提供新的工艺思路,促进生产效率的提升和成本的降低。分析了铝合金激光焊接的工艺特性、技术难点和解决思路,记录利用300W激光对铝合金进行单光束焊接的有关参数和焊接效果,搭建双光束激光焊接试验平台,记录较高功率双光束和总量约500W激光分成双光束焊接试验过程及有关参数。进行了激光、氩弧混合焊接试验。对部分焊接样品进行了定量分析。经过分析研究,提出了铝合金激光焊接工艺改进意见。

  2. Dissimilar joining of galvanized high-strength steel to aluminum alloy in a zero-gap lap joint configuration by two-pass laser welding

    International Nuclear Information System (INIS)

    Ma, Junjie; Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-01-01

    Highlights: • Defect-free two-pass laser partially penetrated lap joint of galvanized steel to aluminum was achieved. • The thickness of the Al-rich intermetallic compounds could be controlled by optimal parameters. • The dynamic behavior of the molten pool and keyhole were monitored by a high speed charge-coupled device camera. • The presence of zinc in the intermetallic compounds could improve the strength of the lap joints. - Abstract: A welding procedure based on using two-pass laser scans is introduced for dissimilar joining of overlapped galvanized high-strength dual-phase (DP) steel DP590 to aluminum alloy (AA) 6061 sheets. The first pass is based on a defocused laser spot that scans across the top of the two overlapped sheets and heats the zinc coating at the faying surface to be melted and partially vaporized, while the second pass is executed with a focused laser spot in order to perform the welding. Completely defect-free galvanized steel to aluminum lap joints were obtained by using this two-pass laser welding procedure. An on-line machine vision system was applied to monitor the keyhole dynamics during the laser welding process. An energy-dispersive X-ray spectroscopy (EDS) was carried out to determine the atomic percent of zinc, aluminum, and iron in the galvanized steel to aluminum lap joints. Mechanical testing and micro-hardness test were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the lap joint of galvanized steel to aluminum obtained by the two-pass laser welding approach had a higher failure value than those joints obtained when the zinc at the faying surface was mechanically removed under the same welding speed and laser power

  3. Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications

    Directory of Open Access Journals (Sweden)

    Mahesh Verma

    2015-01-01

    Conclusions: Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

  4. Fundamental experiment for flash removal of aluminum alloy by CO2 laser beam cutting; CO2 laser beam setsudan ni yoru aluminium gokin no ibaritori no kiso jikken

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Y.; Tokunaga, T. [University of Industrial Technology, Kanagawa (Japan); Miyazaki, T. [Chiba Institute of Technology, Chiba (Japan)

    1995-08-25

    CO2 laser beam has been applied to cut of the aluminum alloy. Average cut width, roughness of cut surface and average thickness of heat affected zone are investigated as functions of laser power, cutting speed and assist gas pressure. The average cut width increases with laser power, but it does not depend on the cutting speed. The narrowest average cut width obtained is 0.22mm under the conditions of laser power of 900W and cutting speeds from 600 to 1000mm/min. The roughness of cut surface decreases with decreasing cutting speed. The best smoothness of cut surface obtained is 17 {mu}m (Rmax) , when the conditions are 1100W and 600mm/min. The average thickness of heat affected zone decreases with increasing assist gas pressure. CO2 laser beam cutting is applicable to flash removal from aluminum alloy casting. This process is expected to reduce the need of physical labor and to improve the working conditions in the foundry industry. 32 refs., 10 figs., 2 tabs.

  5. Experimental and numerical study of spatter formation and composition change in fiber laser welding of aluminum alloy

    Science.gov (United States)

    Wu, Dongsheng; Hua, Xueming; Ye, Youxiong; Huang, Lijin; Li, Fang; Huang, Ye

    2018-05-01

    A laser welding experiment with glass is conducted to directly observe the keyhole behavior and spatter formation in fiber laser welding of aluminum alloy. A 3D model is developed to investigate the spatter formation and composition change. An additional conservation equation is introduced to describe the Mg element distribution, and the Mg element loss due to evaporation is also considered. Based on numerical and experimental results, it is found that the keyhole geometry in laser welding of aluminum alloy is different from that in laser welding of steel. There are three required steps for spatter formation around the keyhole. The high momentum of the molten metal, the high recoil pressure and vapor shear stress, and the low surface tension around the keyhole contribute to the easy formation of spatter. The in-homogeneous distribution of Mg element in the weld can be attributable to the continuous evaporation of Mg element at the top surface of keyhole rear, the upward flow of low Mg element region from the bottom of the keyhole to the top surface of keyhole rear along the fusion line, the collapse of the keyhole, and the ejection of spatters.

  6. Numerical simulation of spatter formation during fiber laser welding of 5083 aluminum alloy at full penetration condition

    Science.gov (United States)

    Wu, Dongsheng; Hua, Xueming; Huang, Lijin; Zhao, Jiang

    2018-03-01

    The droplet escape condition in laser welding is established in this paper. A three-dimensional numerical model is developed to study the weld pool convection and spatter formation at full penetration during the fiber laser welding of 5083 aluminum alloy. It is found that when laser power is 9 kW, the bottom of the keyhole is dynamically opened and closed. When the bottom of the keyhole is closed, the molten metal at the bottom of the back keyhole wall flows upwards along the fusion line. When the bottom of the keyhole is opened, few spatters can be seen around the keyhole at the top surface, two flow patterns exists in the rear part of the keyhole: a portion of molten metal flows upwards along the fusion line, other portion of molten metal flows to the bottom of the keyhole, which promote the spatter formation at the bottom of the keyhole rear wall.

  7. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Napolitani, E. [MATIS IMM-CNR at Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Impellizzeri, G. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Giarola, M. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); De Salvador, D. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Privitera, V.; Priolo, F. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Mariotto, G. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); Carnera, A. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-31

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm{sup −1}, due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm{sup −1}, which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm{sup −1} is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm{sup −1}.

  8. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    International Nuclear Information System (INIS)

    Sanson, A.; Napolitani, E.; Impellizzeri, G.; Giarola, M.; De Salvador, D.; Privitera, V.; Priolo, F.; Mariotto, G.; Carnera, A.

    2013-01-01

    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm −1 , due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm −1 , which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm −1 is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm −1

  9. The development of a quality prediction system for aluminum laser welding to measure plasma intensity using photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ji Young [Technical Research Center, Hyundai Steel Company, Dangjin (Korea, Republic of); Sohn, Yong Ho [Dept. of Materials Science and Engineering, University of Central Florida, Orlando (United States); Park, Young Whan; Kwak, Jae Seob [Dept. of Mechanical Engineering, Pukyong National University, Busan (Korea, Republic of)

    2016-10-15

    Lightweight metals have been used to manufacture the body panels of cars to reduce the weight of car bodies. Typically, aluminum sheets are welded together, with a focus on weld quality assurance. A weld quality prediction system for the laser welding of aluminum was developed in this research to maximize welding production. The behavior of the plasma was also analyzed, dependent on various welding conditions. The light intensity of the plasma was altered with heat input and wire feed rate conditions, and the strength of the weld and sensor signals correlated closely for this heat input condition. Using these characteristics, a new algorithm and program were developed to evaluate the weld quality. The design involves a combinatory algorithm using a neural network model for the prediction of tensile strength from measured signals and a fuzzy multi-feature pattern recognition algorithm for the weld quality classification to improve predictability of the system.

  10. The development of a quality prediction system for aluminum laser welding to measure plasma intensity using photodiodes

    International Nuclear Information System (INIS)

    Yu, Ji Young; Sohn, Yong Ho; Park, Young Whan; Kwak, Jae Seob

    2016-01-01

    Lightweight metals have been used to manufacture the body panels of cars to reduce the weight of car bodies. Typically, aluminum sheets are welded together, with a focus on weld quality assurance. A weld quality prediction system for the laser welding of aluminum was developed in this research to maximize welding production. The behavior of the plasma was also analyzed, dependent on various welding conditions. The light intensity of the plasma was altered with heat input and wire feed rate conditions, and the strength of the weld and sensor signals correlated closely for this heat input condition. Using these characteristics, a new algorithm and program were developed to evaluate the weld quality. The design involves a combinatory algorithm using a neural network model for the prediction of tensile strength from measured signals and a fuzzy multi-feature pattern recognition algorithm for the weld quality classification to improve predictability of the system

  11. Evaluation of Mechanical Properties of Glass Fiber Posts Subjected to Laser Surface Treatments.

    Science.gov (United States)

    Barbosa Siqueira, Carolina; Spadini de Faria, Natália; Raucci-Neto, Walter; Colucci, Vivian; Alves Gomes, Erica

    2016-10-01

    The aim of this study was to evaluate the influence of laser irradiation on flexural strength, elastic modulus, and surface roughness and morphology of glass fiber posts (GFPs). Laser treatment of GFPs has been introduced to improve its adhesion properties. A total of 40 GFPs were divided into 4 groups according to the irradiation protocol: GC-no irradiation, GYAG-irradiation with erbium:yttrium-aluminum-garnet [Er:YAG], GCR-irradiation with erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG), and GDI-irradiation with diode laser. The GFP roughness and morphology were evaluated through laser confocal microscopy before and after surface treatment. Three-point bending flexural test measured flexural strength and elastic modulus. Data about elastic modulus and flexural strength were subjected to one-way ANOVA and Bonferroni test (p properties of GFPs.

  12. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments.

    Science.gov (United States)

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-12-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG.

  13. Parameter prediction for microwave garnets

    International Nuclear Information System (INIS)

    Ramer, R.

    1996-01-01

    Full text: Linearity of the microwave parameters (resonance linewidth ΔH and effective linewidth ΔH eff ) is demonstrated and their use in the Computer-aided design (CAD)/Computer-aided manufacturing (CAM) of new microwave garnets is proposed. Such an approach would combine a numerical database of microwave data and several computational programs. The model is an applied formulation of the analysis of a wide range of microwave garnets

  14. Laser microprobe mass analysis (LAMMA) of aluminum and lead in fine roots and their ectomycorrhizal mantles of Norway spruce (Picea abies (L.) Karst.).

    Science.gov (United States)

    Eeckhaoudt, S; Vandeputte, D; Van Praag, H; Van Grieken, R; Jacob, W

    1992-03-01

    Fine roots and ectomycorrhizal root tips were sampled in a Norway spruce (Picea abies (L.) Karst.) stand in the eastern part of the Belgian Ardennes. The cellular and partly subcellular localizations of aluminum and lead were identified by the micro-analytical laser microprobe mass analysis (LAMMA) technique. In fine roots with secondary structure, localization of aluminum was limited to the peripheral cell layers. Lead was found in the outer layers, and also in the primary phloem. Aluminum penetrated the mycorrhizal mantle, but lead was seldom detected in ectomycorrhizae.

  15. Enhancement of the Wear Resistance and Microhardness of Aluminum Alloy by Nd:YaG Laser Treatment

    Directory of Open Access Journals (Sweden)

    Haitham T. Hussein

    2014-01-01

    Full Text Available Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM, energy-dispersive X-ray florescence analysis (EDS, optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4 : 1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

  16. The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

    Science.gov (United States)

    Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

    2017-11-01

    This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

  17. Ballistic phonon and thermal radiation transport across a minute vacuum gap in between aluminum and silicon thin films: Effect of laser repetitive pulses on transport characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa; Ali, H.

    2016-08-15

    Short-pulse laser heating of aluminum and silicon thin films pair with presence of a minute vacuum gap in between them is considered and energy transfer across the thin films pair is predicted. The frequency dependent Boltzmann equation is used to predict the phonon intensity distribution along the films pair for three cycles of the repetitive short-pulse laser irradiation on the aluminum film surface. Since the gap size considered is within the Casimir limit, thermal radiation and ballistic phonon contributions to energy transfer across the vacuum gap is incorporated. The laser irradiated field is formulated in line with the Lambert's Beer law and it is considered as the volumetric source in the governing equations of energy transport. In order to assess the phonon intensity distribution in the films pair, equivalent equilibrium temperature is introduced. It is demonstrated that thermal separation of electron and lattice sub-systems in the aluminum film, due to the short-pulse laser irradiation, takes place and electron temperature remains high in the aluminum film while equivalent equilibrium temperature for phonons decays sharply in the close region of the aluminum film interface. This behavior is attributed to the phonon boundary scattering at the interface and the ballistic phonon transfer to the silicon film across the vacuum gap. Energy transfer due to the ballistic phonon contribution is significantly higher than that of the thermal radiation across the vacuum gap.

  18. Ballistic phonon and thermal radiation transport across a minute vacuum gap in between aluminum and silicon thin films: Effect of laser repetitive pulses on transport characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.

    2016-08-01

    Short-pulse laser heating of aluminum and silicon thin films pair with presence of a minute vacuum gap in between them is considered and energy transfer across the thin films pair is predicted. The frequency dependent Boltzmann equation is used to predict the phonon intensity distribution along the films pair for three cycles of the repetitive short-pulse laser irradiation on the aluminum film surface. Since the gap size considered is within the Casimir limit, thermal radiation and ballistic phonon contributions to energy transfer across the vacuum gap is incorporated. The laser irradiated field is formulated in line with the Lambert's Beer law and it is considered as the volumetric source in the governing equations of energy transport. In order to assess the phonon intensity distribution in the films pair, equivalent equilibrium temperature is introduced. It is demonstrated that thermal separation of electron and lattice sub-systems in the aluminum film, due to the short-pulse laser irradiation, takes place and electron temperature remains high in the aluminum film while equivalent equilibrium temperature for phonons decays sharply in the close region of the aluminum film interface. This behavior is attributed to the phonon boundary scattering at the interface and the ballistic phonon transfer to the silicon film across the vacuum gap. Energy transfer due to the ballistic phonon contribution is significantly higher than that of the thermal radiation across the vacuum gap.

  19. Ballistic phonon and thermal radiation transport across a minute vacuum gap in between aluminum and silicon thin films: Effect of laser repetitive pulses on transport characteristics

    International Nuclear Information System (INIS)

    Yilbas, B.S.; Ali, H.

    2016-01-01

    Short-pulse laser heating of aluminum and silicon thin films pair with presence of a minute vacuum gap in between them is considered and energy transfer across the thin films pair is predicted. The frequency dependent Boltzmann equation is used to predict the phonon intensity distribution along the films pair for three cycles of the repetitive short-pulse laser irradiation on the aluminum film surface. Since the gap size considered is within the Casimir limit, thermal radiation and ballistic phonon contributions to energy transfer across the vacuum gap is incorporated. The laser irradiated field is formulated in line with the Lambert's Beer law and it is considered as the volumetric source in the governing equations of energy transport. In order to assess the phonon intensity distribution in the films pair, equivalent equilibrium temperature is introduced. It is demonstrated that thermal separation of electron and lattice sub-systems in the aluminum film, due to the short-pulse laser irradiation, takes place and electron temperature remains high in the aluminum film while equivalent equilibrium temperature for phonons decays sharply in the close region of the aluminum film interface. This behavior is attributed to the phonon boundary scattering at the interface and the ballistic phonon transfer to the silicon film across the vacuum gap. Energy transfer due to the ballistic phonon contribution is significantly higher than that of the thermal radiation across the vacuum gap.

  20. Laser cutting of triangular geometry into 2024 aluminum alloy: Influence of triangle size on thermal stress field

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, Bekir Sami; Akhtar, Syed Sohail [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Keles, Omer; Boran, Kurtulus [Gazi University, Ankara (Turkmenistan)

    2015-08-15

    Laser cutting of a triangular geometry into aluminum 2024 alloy is carried out. Thermal stress field in the cutting section is predicted using the finite element code ABAQUS. Surface temperature predictions are validated through the thermocouple data. Morphological changes in the cut section are examined incorporating optical and electron scanning microscopes. The effects of the size of the triangular geometry on thermal stress field are also examined. It is found that surface temperature predictions agree well with thermocouple data. von Mises stress remains high in the region close to the corners of the triangular geometry, which is more pronounced for the small size triangle. This behavior is associated with the occurrence of the high cooling rates in this region. Laser cut edges are free from large scale sideways burning and large size burr attachments. However, some locally scattered dross attachments are observed at the kerf exit.

  1. Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Mo, M. Z.; Chen, Z.; Tsui, Y. Y.; Fedosejevs, R. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Fourmaux, S.; Saraf, A.; Otani, K.; Kieffer, J. C. [INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2 (Canada); Ng, A. [Department of Physics and Astronomy, University of British Columbia, British Columbia V6T 1Z1 (Canada)

    2013-12-15

    We have developed a laser wakefield generated X-ray probe to directly measure the temporal evolution of the ionization states in warm dense aluminum by means of absorption spectroscopy. As a promising alternative to the free electron excited X-ray sources, Betatron X-ray radiation, with femtosecond pulse duration, provides a new technique to diagnose femtosecond to picosecond transitions in the atomic structure. The X-ray probe system consists of an adjustable Kirkpatrick-Baez (KB) microscope for focusing the Betatron emission to a small probe spot on the sample being measured, and a flat Potassium Acid Phthalate Bragg crystal spectrometer to measure the transmitted X-ray spectrum in the region of the aluminum K-edge absorption lines. An X-ray focal spot size of around 50 μm was achieved after reflection from the platinum-coated 10-cm-long KB microscope mirrors. Shot to shot positioning stability of the Betatron radiation was measured resulting in an rms shot to shot variation in spatial pointing on the sample of 16 μm. The entire probe setup had a spectral resolution of ∼1.5 eV, a detection bandwidth of ∼24 eV, and an overall photon throughput efficiency of the order of 10{sup −5}. Approximately 10 photons were detected by the X-ray CCD per laser shot within the spectrally resolved detection band. Thus, it is expected that hundreds of shots will be required per absorption spectrum to clearly observe the K-shell absorption features expected from the ionization states of the warm dense aluminum.

  2. Influence of neodymium-doping on structure and properties of yttrium aluminium garnet

    DEFF Research Database (Denmark)

    Zhang, X.D.; He, W.; Yue, Yuanzheng

    2013-01-01

    We study the impact of the Nd-doping on the grain formation, the crystal structure, and the fluorescence of the Yttrium Aluminum Garnet (YAG). The results show that Nd-doping leads to the YAG lattice expansion and distortion, and hence to an increase in defect concentration. This is attributed to...

  3. A Visualization Method for Corrosion Damage on Aluminum Plates Using an Nd:YAG Pulsed Laser Scanning System.

    Science.gov (United States)

    Lee, Inbok; Zhang, Aoqi; Lee, Changgil; Park, Seunghee

    2016-12-16

    This paper proposes a non-contact nondestructive evaluation (NDE) technique that uses laser-induced ultrasonic waves to visualize corrosion damage in aluminum alloy plate structures. The non-contact, pulsed-laser ultrasonic measurement system generates ultrasonic waves using a galvanometer-based Q-switched Nd:YAG laser and measures the ultrasonic waves using a piezoelectric (PZT) sensor. During scanning, a wavefield can be acquired by changing the excitation location of the laser point and measuring waves using the PZT sensor. The corrosion damage can be detected in the wavefield snapshots using the scattering characteristics of the waves that encounter corrosion. The structural damage is visualized by calculating the logarithmic values of the root mean square (RMS), with a weighting parameter to compensate for the attenuation caused by geometrical spreading and dispersion of the waves. An intact specimen is used to conduct a comparison with corrosion at different depths and sizes in other specimens. Both sides of the plate are scanned with the same scanning area to observe the effect of the location where corrosion has formed. The results show that the damage can be successfully visualized for almost all cases using the RMS-based functions, whether it formed on the front or back side. Also, the system is confirmed to have distinguished corroded areas at different depths.

  4. Influence of repetitive pulsed laser irradiation on the surface characteristics of an aluminum alloy in the melting regime

    International Nuclear Information System (INIS)

    Choi, Sung Ho; Jhang, Kyung Young

    2015-01-01

    We have investigated the influence of repetitive near-infrared (NIR) pulsed laser shots in the melting regime on the surface characteristics of an aluminum 6061-T6 alloy. Characteristics of interest include surface morphology, surface roughness, and surface hardness in the melted zone as well as the size of the melted zone. For this study, the proper pulse energy for inducing surface melting at one shot is selected using numerical simulations that calculate the variation in temperature at the laser beam spot for various input pulse energies in order to find the proper pulse energy for raising the temperature to the melting point. In this study, 130 mJ was selected as the input energy for a Nd:YAG laser pulse with a duration of 5 ns. The size of the melted zone measured using optical microscopy (OM) increased logarithmically with an increasing shot number. The surface morphology observed by scanning electron microscopy (SEM) clearly showed a re-solidified microstructure evolution after surface melting. The surface roughness and hardness were measured by atomic force microscopy (AFM) and nano-indentation, respectively. The surface roughness showed almost no variation due to the surface texturing after laser shots over 10. The hardness inside the melted zone was lower than that outside the zone because the β'' phase was transformed to a β phase or dissolved into a matrix.

  5. New application of the long-pulsed Nd-YAG laser as an ablative resurfacing tool for skin rejuvenation: a 7-year study.

    Science.gov (United States)

    Alshami, Mohammad Ali

    2013-09-01

    Carbon dioxide (CO2 ) and erbium-yttrium aluminum garnet (Er-YAG) lasers are the gold standards in ablative skin resurfacing. Neodymium-doped yttrium aluminum garnet (Nd-YAG) laser is considered a nonablative skin resurfacing laser whose usage is limited due to its high cost. To assess the efficacy and safety of Nd-YAG as an ablative resurfacing laser and to compare the results with those previously published for CO2 and Erbium-YAG lasers. A total of 296 patients (251 female and 45 male) with Fitzpatrick skin types III-IV and dermatological conditions amenable to ablative skin resurfacing participated in this study. Nd-YAG laser parameters assessed were wavelength (1064 nm), pulse duration (5 ms), fluence (10 J/cm(2) ), and spot size (8-10 mm). Efficacy of Nd-YAG laser was assessed by comparing pre- and posttreatment photographs. An improvement of 30-80% was observed in treated patients. The degree of improvement correlated positively with the number of laser sessions. The most common side effect was hyperpigmentation. Other side effects were less common and mild in intensity compared with published results for gold standard ablative lasers. Not only was the Nd-YAG laser found to be as effective as Er-YAG and CO2 lasers, but treated patients also had shorter recovery and treatment times, and at lower cost. © 2013 Wiley Periodicals, Inc.

  6. Effect of adhesive system application for cavities prepared with erbium, chromium: yttrium scandium gallium garnet laser on rat dental pulp tissue.

    Science.gov (United States)

    Takada, Mayo; Suzuki, Masaya; Haga-Tsujimura, Maiko; Shinkai, Koichi

    2017-07-01

    We examined the effects of adhesive systems under study applied for a laser-cut cavity using an Er,Cr:YSGG laser on rat dental pulp at 24 h and 14 days postoperatively. Group 1, laser-cut cavities were treated with a self-etching-primer and bonding agent; group 2, pretreated with a phosphoric-acid, and then treated with a self-etching-primer and bonding agent; group 3, pretreated with a phosphoric-acid and sodium-hypochlorite, and then treated with a self-etching-primer and bonding agent; and group 4, treated with an all-in-one adhesive. A flowable resin composite was used as filling material for each cavity treated with each group. A glass-ionomer-cement was used as a control. The following items were evaluated: pulp-tissue-disorganization (PTD), inflammatory-cell-infiltration (ICI), tertiary-dentin-formation (TDF), and bacterial-penetration (BP). The results were statistically analyzed using the Kruskal-Wallis test and Mann-Whitney U test. No significant differences were observed among the experimental groups for all parameters after 24 h and 14 days (P > 0.05). The majority of the specimens showed PTD with edema formation after 24 h; however, all the specimens demonstrated pulpal healing with TDF after 14 days. On the parameter of TDF, all groups showed significant differences between the two postoperative periods (P < 0.01). On the parameter of ICI, a significant difference was found between the two postoperative periods in group 4 (P < 0.05). No specimens showed BP. The pretreatment on the cavity prepared with the laser using phosphoric-acid or sodium-hypochlorite did not affect the dental pulp healing of rat tooth.

  7. Laser surface alloying of aluminum (AA1200) with Ni and SiC Powders

    CSIR Research Space (South Africa)

    Mabhali, Luyolo AB

    2010-12-01

    Full Text Available . The dissociated C reacted with Al to form Al4C3. The addition of Ni resulted in the formation of the Al3Ni phase. A hardness increase of approximately four times that of aluminum AA1200 was achieved in the alloyed layer....

  8. Correlations between optical properties, microstructure, and processing conditions of Aluminum nitride thin films fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Baek, Jonghoon; Ma, James; Becker, Michael F.; Keto, John W.; Kovar, Desiderio

    2007-01-01

    Aluminum nitride (AlN) films were deposited using pulsed laser deposition (PLD) onto sapphire (0001) substrates with varying processing conditions (temperature, pressure, and laser fluence). We have studied the dependence of optical properties, structural properties and their correlations for these AlN films. The optical transmission spectra of the produced films were measured, and a numerical procedure was applied to accurately determine the optical constants for films of non-uniform thickness. The microstructure and texture of the films were studied using various X-ray diffraction techniques. The real part of the refractive index was found to not vary significantly with processing parameters, but absorption was found to be strongly dependent on the deposition temperature and the nitrogen pressure in the deposition chamber. We report that low optical absorption, textured polycrystalline AlN films can be produced by PLD on sapphire substrates at both low and high laser fluence using a background nitrogen pressure of 6.0 x 10 -2 Pa (4.5 x 10 -4 Torr) of 99.9% purity

  9. Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Tatsuya [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: kiku@eng.hokudai.ac.jp; Sakairi, Masatoshi [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, Hideaki [Asahikawa National College of Technology, Syunkohdai, 2-2, 1-6, Asahikawa 071-8142 (Japan)

    2009-11-30

    Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-{mu}m wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing.

  10. Multi-kiloampere, electron-beam generation from bare aluminum photo-cathodes driven by an ArF laser

    International Nuclear Information System (INIS)

    Carlson, R.L.; Ridlon, R.N.; Seitz, G.J.; Hughes, T.P.

    1997-01-01

    An electron-beam-pumped laser operating at ArF (193 nm) producing up to 5.0 joules in a 150-ns pulse has been used to illuminate micro-machined aluminum cathodes. The cathode was pulsed from 2.25- up to 2.95-MV across a 20-cm-AK gap producing fields up to 145 kV/cm using REX (a 4-MeV, 5-kA, 100-ns pulsed diode). Extracted current versus laser power gives a quantum efficiency increasing with power density from 0.07 to 0.11%. The present work is significant in that the cathode operates in the presence of out-gassing materials with a background vacuum pressure in the mid 10 -6 torr region and 100-ns-long electron beams of up to 3 kA have been produced. Both emission limited (current follows laser pulse) and space-charge-limited (current follows pulsed power) regimes have been studied up to ∼ 50 A/cm 2 by varying the cathode diameter. The beam temperature has been measured to be < 5 eV and directly compared in the same experimental setup to velvet based cathodes that measure ∼ 100 eV

  11. Developing the model of laser ablation by considering the interplay between emission and expansion of aluminum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, F.; Tavassoli, S. H. [Laser and Plasma Research Institute, ShahidBeheshti University, 19396 4716, G. C., Evin, Tehran (Iran, Islamic Republic of)

    2013-01-15

    In the present study, the ablation behavior of aluminum target and its plasma radiation in noble ambient gases by a laser pulse with wavelength of 266 nm and pulse duration of 10 ns are numerically studied. A thermal model of laser ablation considering heat conduction, Euler equations, Saha-Eggert equations, Knudsen layer, mass and energy balance relations and optical shielding effects are used for calculation of plasma parameters. Effects of excitation energy on plasma expansion and its emissivity are investigated. Time and spatial-resolved plasma emission including bremsstrahlung, recombination and spectral emission at early delay times after laser irradiation is obtained. Effects of two ambient gases (He and Ar) as well as different gas pressures of 100, 300, 500, and 760 Torr on plasma expansion and its spectrum are studied. Results illustrate that at initial delay times, especially at high noble gas pressures, ionic lines have the maximum intensities, while at later times neutral lines dominate. When the pressure of ambient gas increases, a confinement of the plasma plume is predicted and the intensity of neutral lines decreases. Continuous emission increases with wavelength in both ambient gases. Spatially resolved analysis shows that an intense continuous emission is predicted next to the sample surface decreasing with distance from the latter.

  12. Improvement of aluminum drilling efficiency and precision by shaped femtosecond laser

    International Nuclear Information System (INIS)

    Qi, Ying; Qi, Hongxia; Chen, Anmin; Hu, Zhan

    2014-01-01

    Highlights: • The ablation accuracy can be improved by the shaped femtosecond laser pulse. • The ablation rate can be improved by the shaped femtosecond laser pulse with higher laser fluence. • The results can be used to optimize femtosecond micromachining metal. - Abstract: Shaped femtosecond laser pulses with the plain phase (transform-limited pulse) and sine phase (A = 1.2566, T = 30, T = 10, and T = 5) were used to drill Al sheet in vacuum. Using different phase, the number of pulses required to drill through the sheet was different. With lower laser pulse energy, the ablation rate was the highest when plain phase (corresponding to transform limited pulse) was used. With higher laser energy, the optimized ablation rate can be achieved by increasing the time separation between the subpulses of pulse train produced from the sine phase function. And, with the shaped femtosecond laser, the diameter of ablation holes produced was smaller, the ablation precision was also improved. The results showed that shaped femtosecond laser pulse has great advantages in the context of femtosecond laser drilling

  13. Influence of surrounding gas, composition and pressure on plasma plume dynamics of nanosecond pulsed laser-induced aluminum plasmas

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-10-01

    Full Text Available In this article, we present a comprehensive study of the plume dynamics of plasmas generated by laser ablation of an aluminum target. The effect of both ambient gas composition (helium, nitrogen or argon and pressure (from ∼5 × 10−7 Torr up to atmosphere is studied. The time- and space- resolved observation of the plasma plume are performed from spectrally integrated images using an intensified Charge Coupled Device (iCCD camera. The iCCD images show that the ambient gas does not significantly influence the plume as long as the gas pressure is lower than 20 Torr and the time delay below 300 ns. However, for pressures higher than 20 Torr, the effect of the ambient gas becomes important, the shortest plasma plume length being observed when the gas mass species is highest. On the other hand, space- and time- resolved emission spectroscopy of aluminum ions at λ = 281.6 nm are used to determine the Time-Of-Flight (TOF profiles. The effect of the ambient gas on the TOF profiles and therefore on the propagation velocity of Al ions is discussed. A correlation between the plasma plume expansion velocity deduced from the iCCD images and that estimated from the TOF profiles is presented. The observed differences are attributed mainly to the different physical mechanisms governing the two diagnostic techniques.

  14. On fabrication procedures of Li-ion conducting garnets

    Energy Technology Data Exchange (ETDEWEB)

    Hanc, Emil [The Mineral and Energy Economy Research Institute, Polish Academy of Sciences, ul. Wybickiego 7, 31-261 Kraków (Poland); Zając, Wojciech, E-mail: wojciech.zajac@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland); Lu, Li; Yan, Binggong; Kotobuki, Masashi [Materials Science Group, Department of Mechanical Engineering, National University of Singapore (Singapore); Ziąbka, Magdalena [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Kraków (Poland); Molenda, Janina [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland)

    2017-04-15

    Ceramic oxides exhibiting high lithium-ion mobility at room temperature receive broad attention as candidate electrolytes for lithium batteries. Lithium-stuffed garnets from the Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} group seem to be especially promising because of their high ionic conductivity at room temperature and their electrochemical stability. In this work, we discuss factors that affect formation of the garnet in its bulk form or in the form of thick and thin films. We demonstrate that zinc oxide can be applied as a sintering aid that facilitate the formation of the highly conducting cubic Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} garnet phase in a single-step sintering procedure. Based on our experience with the single-step sintering experiments, we successfully fabricated a thick-film membrane consisting of a garnet solid electrolyte using the tape casting technique. In order to reduce the thickness of the electrolyte even further we investigated the fabrication of a thin-film Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} electrolyte by means of the pulsed laser deposition technique.

  15. Mechanical properties and microstructure of stir casted Al/B{sub 4}C/garnet composites

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rathinam Ashok [Chendhuran College of Engineering and Technology, Tamil Nadu (India). Mechanical Engineering Dept.; Sait, Abdullah Naveen [Chendhuran College of Engineering and Technology, Tamil Nadu (India); Subramanian, Karuppazhi [Government College of Engineering, Tamil Nadu (India). Dept. of Mechanical Engineering

    2017-05-01

    Aluminum based metal matrix composites are one of the advanced engineering materials that have been developed for low weight and high strength applications in automotive industries due to high specific strength and good wear resistance. In this context, aluminum alloy boron carbide and garnet composites were fabricated by the stir casting process. The microstructural examination was done by using a scanning electron microscope to assess the distribution of particulates in the aluminum matrix. The composites were characterized by hardness and tensile tests. The wear behavior of the composites was analyzed with the help of a pin-on-disc wear test. By increasing the amount of garnet in the composite, it has been observed that the tensile strength and hardness increase. The wear test analysis proved that the addition of reinforcements reduces the wear rate behavior of composite.

  16. Local thermodynamic equilibrium and related metrological issues involving collisional-radiative model in laser-induced aluminum plasmas

    International Nuclear Information System (INIS)

    Travaille, G.; Peyrusse, O.; Bousquet, B.; Canioni, L.; Pierres, K. Michel-Le; Roy, S.

    2009-01-01

    We present a collisional-radiative approach of the theoretical analysis of laser-induced breakdown spectroscopy (LIBS) plasmas. This model, which relies on an optimized effective potential atomic structure code, was used to simulate a pure aluminum plasma. The description of aluminum involved a set of 220 atomic levels representative of three different stages of ionization (Al 0 , Al + and Al ++ ). The calculations were carried for stationary plasmas, with input parameters (n e and T e ) ranging respectively between 10 13-18 cm -3 and 0.3-2 eV. A comparison of our atomic data with some existing databases is made. The code was mainly developed to address the validity of the local thermodynamic equilibrium (LTE) assumption. For usual LIBS plasma parameters, we did not reveal a sizeable discrepancy of the radiative equilibrium of the plasma towards LTE. For cases where LTE was firmly believed to stand, the Boltzmann plot outputs of this code were used to check the physical accuracy of the Boltzmann temperature, as it is currently exploited in several calibration-free laser-induced breakdown spectroscopy (CF-LIBS) studies. In this paper, a deviation ranging between 10 and 30% of the measured Boltzmann temperature to the real excitation temperature is reported. This may be due to the huge dispersion induced on the line emissivities, on which the Boltzmann plots are based to extract this parameter. Consequences of this fact on the CF-LIBS procedure are discussed and further insights to be considered for the future are introduced.

  17. Acceleration of protons in plasma produced from a thin plastic or aluminum target by a femtosecond laser

    International Nuclear Information System (INIS)

    Rosinski, M.; Badziak, J.; Parys, P.; Zaras-Szydlowska, A.; Ryc, L.; Makowski, J.; Torrisi, L.; Szydlowski, A.; Malinowska, A.; Kaczmarczyk, B.; Torrisi, A.

    2016-01-01

    The acceleration of protons in plasma produced from thin mylar (3.5 μ m) and aluminum (2 μm) targets by a 45-fs laser pulses with the energy of 400 mJ and the intensity of up to 10 19 W/cm 2 was investigated. Characteristics of forward-accelerated protons were measured by the time-of-flight method. In the measurements, special attention was paid to the dependence of proton beam parameters on the laser focus position (FP) in relation to the target surface which resulted in the intensity change within a factor of ∼ 10. It was observed that in the case of using the Mylar target, the dependence of both the maximum ( E pmax ) and the mean (( E p )) proton energy on |Δ x | is clearly non-symmetric with regard to the point where FP = 0 (the focal plane on the target surface) and highest proton energies are achieved when the focal plane is situated in front of the target. In particular, for the target with the thickness of 3.5 μ m E pmax reached 2.2 MeV for FP = +50 μm while for FP = 0 and FP = −100 μm the maximum proton energies reached only 1.6 MeV and 1.3 MeV, respectively. For the aluminum target of 2 μm thickness E p changed only within ∼ 40% and the highest proton energies reached 2.4 MeV.

  18. ENHANCEMENT OF THE CORROSION RESISTANCE FOR 6009 ALUMINUM ALLOY BY LASER TREATMENT

    Directory of Open Access Journals (Sweden)

    Abdulhadi K. Judran

    2018-05-01

    Full Text Available Using laser in modifying the surfaces of various materials is an important topic in the present time. The type of alloy used in this investigation was 6009Al alloy. Laser has been used as inhibitor to reduce the corrosion rate by using Q-switching Nd: YAG Laser (with changing energy of laser and fixing other parameters under laser shock peening (LSP technique for 6009 AA in hydrochloric acid with concentration of 1 M and the immersion time of 30 minutes at room temperature. The corrosion rate was calculated by using the polarization method. The corrosion rate decreased from (0.366 to 0.016 mm/yr before and after using LSP, respectively. Therefore, this study aims to reduce the corrosion rate that occurs in 6009 Al alloy.

  19. Experimental determination of the temperature range of AlO molecular emission in laser-induced aluminum plasma in air

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Xueshi; Motto-Ros, Vincent [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon Villeurbanne (France); Lei, Wenqi [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon Villeurbanne (France); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Zheng, Lijuan [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Yu, Jin, E-mail: jin.yu@univ-lyon1.fr [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon Villeurbanne (France); Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astrophysics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2014-09-01

    Measurements with laser-induced breakdown spectroscopy (LIBS) usually take place in the atmospheric air. For quantitative analysis of metallic elements, oxidation may represent an important issue which can significantly modify the stoichiometry of the plasma. Molecule formation in plasma should be therefore studied and taken into account in the LIBS practice. In this work, we experimentally investigated the temporal evolution and transformation of the plasma induced on an aluminum target by a nanosecond infrared (1064 nm) laser in the atmospheric air, in terms of its temperatures over a large interval of time from hundreds of nanoseconds to tens of microseconds. Such evolution was then correlated to the temporal evolution of the emission intensity from AlO molecules in the ablation plume. In particular, for a given ablation laser pulse energy, the appearance of the molecular emission while the plume cools down allows determining a minimal delay, τ{sub min}, which corresponds to a maximal value of the temperature, T{sub max}, below which the molecular emission begins to be clearly observed and to grow as a function of the delay. Such delay or such temperature indicates the longest delay or the lowest temperature for laser-induced plasma to be suitable for a correct analysis of metallic elements without significant influence of the alternation of the stoichiometry by oxidation. In our experiment, the values of τ{sub min} and T{sub max} have been determined for a range of ablation laser pulse energies from 5 mJ to 50 mJ. These values lie respectively in the range of 3 to 15 μs for τ{sub min}, and 4500 K to 6600 K in terms of the molecule temperature for T{sub max}. Beyond the practical interest for LIBS, our results provide also insights to the kinetics of the AlO molecule formation in laser-induced plasma. - Highlights: • Determination of the temperatures in laser-induced plasma up to tens of microseconds • Determination of the molecule temperature by fitting

  20. Prevention of pharyngocutaneous fistulas by means of laser-weld techniques.

    Science.gov (United States)

    Shohet, J A; Reinisch, L; Ossoff, R H

    1995-07-01

    Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

  1. Fusion cutting of aluminum, magnesium, and titanium alloys using high-power fiber laser

    Science.gov (United States)

    Scintilla, Leonardo Daniele; Tricarico, Luigi

    2013-07-01

    The effects of cutting speed and assist gas pressure on laser cutting of 1-mm thick Al 1050, AZ31, and Ti6Al4V lightweight alloys are experimentally investigated. Fiber laser cutting of these materials is not broadly investigated and the acquisition of a new level of knowledge is of fundamental importance for applications like sheet metal trimming in automotive industry. The main process outputs are in depth compared with results reported in literature and obtained by cutting with CO2 and Nd∶YAG lasers. The good cut quality, the high productivity, and the easy delivery of the beam obtained at the same time, corroborate the advantage of using fiber lasers for thin sheets lightweight alloys cutting.

  2. Femtosecond laser inscribed cladding waveguides in Nd:YAG ceramics: fabrication, fluorescence imaging and laser performance.

    Science.gov (United States)

    Liu, Hongliang; Jia, Yuechen; Vázquez de Aldana, Javier Rodríguez; Jaque, Daniel; Chen, Feng

    2012-08-13

    We report on the fabrication of depressed cladding waveguide lasers in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) ceramics microstructured by femtosecond laser pulses. Full control over the confined light spatial distribution is demonstrated by the fabrication of high contrast waveguides with hexagonal, circular and trapezoidal configurations. The confocal fluorescence measurements of the waveguides reveal that the original luminescence features of Nd3+ ions are well-preserved in the waveguide regions. Under optical pump at 808 nm, cladding waveguides showed continuous wave efficient laser oscillation. The maximum output power obtained at 1064.5 nm is ~181 mW with a slope efficiency as high as 44%, which suggests that the fabricated Nd:YAG ceramic waveguides are promising candidates for efficient integrated laser sources.

  3. Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

    Energy Technology Data Exchange (ETDEWEB)

    Bin Mansoor, Saad; Sami Yilbas, Bekir, E-mail: bsyilbas@kfupm.edu.sa

    2015-08-15

    Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system.

  4. Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

    International Nuclear Information System (INIS)

    Bin Mansoor, Saad; Sami Yilbas, Bekir

    2015-01-01

    Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system

  5. Stand-off laser-induced breakdown spectroscopy of aluminum and geochemical reference materials at pressure below 1 torr

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang-Jae; Choi, Soo-Jin; Yoh, Jack J., E-mail: jjyoh@snu.ac.kr

    2014-11-01

    Laser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopy that utilizes a highly irradiated pulse laser focused on the target surface to produce plasma. We obtain spectroscopic information from the microplasma and determine the chemical composition of the sample based on its elemental and molecular emission peaks. We develop a stand-off LIBS system to analyze the effect of the remote sensing of aluminum and various geochemical reference materials at pressures below 1 torr. Using a commercial 4 inch refracting telescope, our stand-off LIBS system is configured at a distance of 7.2 m from the four United States Geological Survey (USGS) geochemical samples that include granodiorite, quartz latite, shale-cody, and diabase, which are selected for planetary exploration. Prepared samples were mixed with a paraffin binder containing only hydrogen and carbon, and were pelletized for experimental convenience. The aluminum plate sample is considered as a reference prior to using the geochemical samples in order to understand the influence of a low pressure condition on the resulting LIBS signal. A Q-switched Nd:YAG laser operating at 1064 nm and pulsed at 10 Hz with 21.7 to 48.5 mJ/pulse was used to obtain signals, which showed that the geochemical samples were successfully detected by the present stand-off detection scheme. A low pressure condition generally results in a decrease of the signal intensity, while the signal to noise ratio can vary according to the samples and elements of various types. We successfully identified the signals at below 1 torr with stand-off detection by a tightly focused light detection and by using a relatively larger aperture telescope. The stand-off LIBS detection at low pressure is promising for potential detection of the minor elements at pressures below 1 torr. - Highlights: • Stand-off LIBS signals at below 1 torr are compared to those of in-situ conditions. • Vacuum condition provides easier detection of the

  6. Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

    Science.gov (United States)

    Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

    2018-03-01

    To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

  7. Magnetooptical garnet films: preparation, characterisation, application

    International Nuclear Information System (INIS)

    Goernert, P.; Lorenz, A.; Lindner, M.; Richert, H.

    2007-01-01

    Full text: In contemporary magnetooptics both Kerr effect and Faraday effect are applied. The Kerr effect of metals and alloys - such as Fe, Ni, Co, FePt, CoPt, MnBi, PtMnSb - with thicknesses 300 μm are established as commercial isolators in optical systems and for developments of waveguide applications. Bi-REIG is prepared mostly by conventional liquid phase epitaxy (LPE) in PbO-B 2 O 3 -Bi 2 O 3 based solvents and sometimes by laser ablation and as nanocrystalline powders. In each case high Faraday rotation and low optical absorption is necessary. Additionally, magnetooptical sensors should possess high sensitivity and a large dynamic range. All these demands can be fulfilled with (REBi) 3 (FeGaAl) 5 O 12 LPE layers. Here we discuss some new results concerning preparation, characterisation, and application of Bi-TmIG and Bi-DyIG LPE layers on high-quality gadolinium gallium garnet (GGG) or lattice matched Ca-, Mg-, Zr-substituted GGG substrates. Optimization of flux melt composition and under cooling result in sensor films with a Faraday rotation of e.g. -1.2 0 /μm at a wavelength of l=590 nm and saturation induction of Bs=70 mT. Such films are already applied for forensic investigations. However, the responsivity of the garnet films is restricted by their coercivity Hc. Surface defects are found to give rise to pinned magnetic domains correlated with typical hysteresis. Obviously, Hc and the formation of pits are due to misfit stress and substrate surface quality. Besides, it is shown that an increase of working temperature leads to smaller coercivities. (authors)

  8. Pulsed laser deposition of aluminum-doped ZnO films at 355 nm

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Thestrup Nielsen, Birgitte

    2004-01-01

    Conducting, transparent films of aluminium-doped ZnO (AZO) have been produced at the laser wavelength 355 nm. The most critical property, the electric resistivity, is up to a factor of 8 above that for films produced at shorter wavelengths. In contrast, the transmission of visible light through...

  9. Local deposition of polypyrrole on aluminum by anodizing, laser irradiation, and electrolytic polymerization and its application to the fabrication of micro-actuators

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, Y. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan); Kikuchi, T. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan)]. E-mail: kiku@elechem1-mc.eng.hokudai.ac.jp; Ueda, M. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan); Iida, M. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan); Sakairi, M. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan); Takahashi, H. [Graduate School of Engineering, Hokkaido University, N13 W8 Kita-Ku, Sapporo (Japan)

    2006-06-15

    Polypyrrole was deposited at selected areas on aluminum by anodizing, laser irradiation, and electrolytic polymerization, and the application of the technique for fabricating micro-actuators was attempted. Aluminum specimens covered with porous type anodic oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally, and then thin Ni layers were deposited at areas where film had been removed. Polypyrrole could be successfully deposited only on the Ni layer by anodic polarization of the specimens in pyrrole monomer solution, and a polypyrrole/Ni bilayer structure could be obtained by dissolution of the aluminum substrate and anodic oxide film in NaOH solutions. The bilayer structure was found to be inactive to doping and dedoping of ions during anodic and cathodic polarization. A three-layer structure, nitrocellulose/Ni/polypyrrole, fabricated by electrolytic polymerization after nitrocellulose coating on a Ni layer detached from the aluminum substrate, showed ion-doping and -dedoping activity, suggesting the possibility of fabricating micro-actuators in this manner.

  10. Best laser for prostatectomy in the year 2013

    Directory of Open Access Journals (Sweden)

    Pankaj N Maheshwari

    2013-01-01

    Full Text Available Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer′s prostatectomy. Green light laser has a short learning curve, is nearly blood-less with good immediate results. Thulium laser is a faster cutting laser while diode laser is a portable laser device. Often laser prostatectomy is considered as a replacement for the standard transurethral resection of prostate (TURP. To be comparable, laser should reduce or avoid the immediate and long-term complications of TURP, especially bleeding and need for blood transfusion. It should also be safe in the ever increasing patient population on antiplatelet and anticoagulant drugs. We need to take stock of the situation and identify, which among the present day lasers has stood the test of time. A review of the literature was performed to see if any of these lasers could be called the "best laser for prostatectomy in 2013."

  11. Best laser for prostatectomy in the year 2013.

    Science.gov (United States)

    Maheshwari, Pankaj N; Joshi, Nitin; Maheshwari, Reeta P

    2013-07-01

    Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer's prostatectomy. Green light laser has a short learning curve, is nearly blood-less with good immediate results. Thulium laser is a faster cutting laser while diode laser is a portable laser device. Often laser prostatectomy is considered as a replacement for the standard transurethral resection of prostate (TURP). To be comparable, laser should reduce or avoid the immediate and long-term complications of TURP, especially bleeding and need for blood transfusion. It should also be safe in the ever increasing patient population on antiplatelet and anticoagulant drugs. We need to take stock of the situation and identify, which among the present day lasers has stood the test of time. A review of the literature was performed to see if any of these lasers could be called the "best laser for prostatectomy in 2013."

  12. Intraoperative localized urticarial reaction during Q-switched Nd:YAG laser tattoo removal.

    Science.gov (United States)

    Wilken, Reason; Ho, Derek; Petukhova, Tatyana; Jagdeo, Jared

    2015-03-01

    Q-switched lasers, such as the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, are the gold standard for tattoo removal. Allergy to tattoo pigment is well-documented, but adverse allergic reactions during or shortly after laser tattoo removal are rare with few reports in the medical literature. Here we describe an intraoperative, localized urticarial reaction that developed during treatment of a tattoo using a 1064-nm Nd:YAG laser. As laser tattoo removal becomes increasingly popular amongst our patients, it is important for dermatologists to be aware of urticarial allergic reactions as well as their management. We outline our recommendations for medical management of this condition and hope that these guidelines will facilitate patient care by dermatologists who encounter this immune skin reaction to laser tattoo removal

  13. Experimental study of solar pumped laser for magnesium-hydrogen energy cycle

    International Nuclear Information System (INIS)

    Yabe, T; Okamoto, Y; Ohkubo, T; Uchida, S; Yoshida, K; Bagheri, B; Funatsu, T; Mabuti, A; Oyama, A; Nakagawa, K; Oishi, T; Daito, K; Nakatsuka, M; Yoshida, M; Motokoshi, S; Sato, Y; Baasandash, C; Nakayama, N; Yanagaidani, K

    2008-01-01

    24.4 W of laser output has been obtained by sun-pumped, Cr-codoped Nd:yttrium aluminum garnet ceramic. The water-cooled laser rod was pumped with a Fresnel lens focusing the natural sunlight. By using the advantages of the Fresnel lenses, the maximum output for unit area of sunlight was 18.7 W/m 2 . Direct concentrated solar illumination was used to pump a 9mm-diameter, 100mm length rod of Cr:Nd:YAG, which was obtained 9%-14% slope efficiency for the laser output. We have analyzed the Cr:YAG laser medium and found it to be an excellent high-power laser candidate for direct solar-pumping schemes which enhances the laser output about 1.8 times more than Nd:YAG

  14. Studies on post weld heat treatment of dissimilar aluminum alloys by laser beam welding technique

    Science.gov (United States)

    Srinivas, B.; Krishna, N. Murali; Cheepu, Muralimohan; Sivaprasad, K.; Muthupandi, V.

    2018-03-01

    The present study mainly focuses on post weld heat treatment (PWHT) of AA5083 and AA6061 alloys by joining these using laser beam welding at three different laser power and two different beam spot sizes and three different welding speeds. Effects of these parameters on microstructural and mechanical properties like hardness, tensile strength were studied at PWHT condition and significant changes had been observed. The PWHT used was artificial aging technique. The microstructural observations revealed that there was a appreciable changes were taken place in the grain size. The microhardness observations proven that the change in the hardness profile in AA6061 was appreciable than in the AA5083. The tensile strength of 246 MPa was recorded as highest. The fractured surfaces observed are predominantly ductile in nature.

  15. Statistical analysis of process parameters to eliminate hot cracking of fiber laser welded aluminum alloy

    Science.gov (United States)

    Wang, Jin; Wang, Hui-Ping; Wang, Xiaojie; Cui, Haichao; Lu, Fenggui

    2015-03-01

    This paper investigates hot cracking rate in Al fiber laser welding under various process conditions and performs corresponding process optimization. First, effects of welding process parameters such as distance between welding center line and its closest trim edge, laser power and welding speed on hot cracking rate were investigated experimentally with response surface methodology (RSM). The hot cracking rate in the paper is defined as ratio of hot cracking length over the total weld seam length. Based on the experimental results following Box-Behnken design, a prediction model for the hot cracking rate was developed using a second order polynomial function considering only two factor interaction. The initial prediction result indicated that the established model could predict the hot cracking rate adequately within the range of welding parameters being used. The model was then used to optimize welding parameters to achieve cracking-free welds.

  16. The microstructure of the surface layer of magnesium laser alloyed with aluminum and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dziadoń, Andrzej [Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, Al. Tysiąclecia P.P. 7, 25-314 Kielce (Poland); Mola, Renata, E-mail: rmola@tu.kielce.pl [Faculty of Mechatronics and Mechanical Engineering, Kielce University of Technology, Al. Tysiąclecia P.P. 7, 25-314 Kielce (Poland); Błaż, Ludwik [Department of Structure and Mechanics of Solids, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland)

    2016-08-15

    The surface layer under analysis was formed as a result of diffusion bonding of a thin AlSi20 plate to a magnesium substrate followed by laser melting. Depending on the process parameters, the laser beam melted the AlSi20 plate only or the AlSi20 plate and a layer of the magnesium surface adjacent to it. Two types of microstructure of the remelted layer were thus analyzed. If the melting zone was limited to the AlSi20 plate, the microstructure of the surface layer was typical of a rapidly solidified hypereutectic Al–Si alloy. Since, however, the liquid AlSi20 reacted with the magnesium substrate, the following intermetallic phases formed: Al{sub 3}Mg{sub 2}, Mg{sub 17}Al{sub 12} and Mg{sub 2}Si. The microstructure of the modified surface layer of magnesium was examined using optical, scanning electron and transmission electron microscopy. The analysis of the surface properties of the laser modified magnesium revealed that the thin layer has a microstructure of a rapidly solidified Al–Si alloy offering good protection against corrosion. By contrast, the surface layer containing particles of intermetallic phases was more resistant to abrasion but had lower corrosion resistance than the silumin type layer. - Highlights: •A CO{sub 2} laser was used for surface alloying of Mg with AlSi20. •Before alloying, an AlSi20 plate was diffusion bonded with the Mg substrate. •The process parameters affected the alloyed layer microstructure and properties. •With melting limited to AlSi20, the layer had a structure of rapidly solidified AlSi20. •Mg–Al and Mg–Si phases were present when both the substrate and the plate were melted.

  17. Shock pressure induced by 0.44 mu m laser radiation on aluminum targets

    Czech Academy of Sciences Publication Activity Database

    Batani, D.; Stabile, H.; Ravasio, A.; Desai, T.; Lucchini, G.; Strati, F.; Ullschmied, Jiří; Krouský, Eduard; Skála, Jiří; Králiková, Božena; Pfeifer, Miroslav; Kadlec, Christelle; Mocek, Tomáš; Präg R., Ansgar; Nishimura, H.; Ochi, Y.; Kilpio, A.; Shashkov, E.; Stuchebrukhov, I.; Vovchenko, V.; Krasuyk, I.

    2003-01-01

    Roč. 21, č. 4 (2003), s. 481-487 ISSN 0263-0346 R&D Projects: GA MŠk LN00A100 Grant - others:HPRI-CT(XX) 1999-00053 Institutional research plan: CEZ:AV0Z2043910 Keywords : rear target luminosity, shock pressure, shock waves Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.646, year: 2003

  18. The microstructure of the surface layer of magnesium laser alloyed with aluminum and silicon

    International Nuclear Information System (INIS)

    Dziadoń, Andrzej; Mola, Renata; Błaż, Ludwik

    2016-01-01

    The surface layer under analysis was formed as a result of diffusion bonding of a thin AlSi20 plate to a magnesium substrate followed by laser melting. Depending on the process parameters, the laser beam melted the AlSi20 plate only or the AlSi20 plate and a layer of the magnesium surface adjacent to it. Two types of microstructure of the remelted layer were thus analyzed. If the melting zone was limited to the AlSi20 plate, the microstructure of the surface layer was typical of a rapidly solidified hypereutectic Al–Si alloy. Since, however, the liquid AlSi20 reacted with the magnesium substrate, the following intermetallic phases formed: Al 3 Mg 2 , Mg 17 Al 12 and Mg 2 Si. The microstructure of the modified surface layer of magnesium was examined using optical, scanning electron and transmission electron microscopy. The analysis of the surface properties of the laser modified magnesium revealed that the thin layer has a microstructure of a rapidly solidified Al–Si alloy offering good protection against corrosion. By contrast, the surface layer containing particles of intermetallic phases was more resistant to abrasion but had lower corrosion resistance than the silumin type layer. - Highlights: •A CO 2 laser was used for surface alloying of Mg with AlSi20. •Before alloying, an AlSi20 plate was diffusion bonded with the Mg substrate. •The process parameters affected the alloyed layer microstructure and properties. •With melting limited to AlSi20, the layer had a structure of rapidly solidified AlSi20. •Mg–Al and Mg–Si phases were present when both the substrate and the plate were melted.

  19. Studies of the mechanisms involved in the laser surface hardening process of aluminum base alloys

    International Nuclear Information System (INIS)

    Silva, Luciana Ventavele da

    2011-01-01

    The Al-Si alloys are widely used in industry to replace the steel and gray cast iron in high-tech sectors. The commercial importance of these alloys is mainly due to its low weight, excellent wear (abrasion) and corrosion resistance, high resistance at elevated temperatures, low coefficient of thermal expansion and lesser fuel consumption that provide considerable reduction of emission of pollutants. In this work, Al-Si alloy used in the automotive industry to manufacture pistons of internal combustion engines, was undergone to surface treatments using LASER remelting (Nd:YAG, λ = 1.06 μm, pulsed mode). The LASER enables various energy concentrations with accurate transfer to the material without physical contact. The intense energy transfer causes the occurrence of structural changes in the superficial layer of the material. Experiments with single pulses and trails were conducted under various conditions of LASER processing in order to analyze microstructural changes resulting from treatments and their effects on the hardness. For the characterization of hardened layer was utilized the following techniques: optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray mapping, Vickers microhardness and maximum roughness tests. The high cooling rate caused a change in the alloy structure due to the refinement of the primary eutectic silicon particles, resulting in increase of the mechanical properties (hardness) of the Al-Si alloy. (author)

  20. Stoichiometry and characterization of aluminum oxynitride thin films grown by ion-beam-assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zabinski, J.S. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Hu, J.J. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)], E-mail: Jianjun.Hu@WPAFB.AF.MIL; Bultman, J.E. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Pierce, N.A. [Propulsion Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Voevodin, A.A. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

    2008-07-31

    Oxides are inherently stable in air at elevated temperatures and may serve as wear resistant matrices for solid lubricants. Aluminum oxide is a particularly good candidate for a matrix because it has good diffusion barrier properties and modest hardness. Most thin film deposition techniques that are used to grow alumina require high temperatures to impart crystallinity. Crystalline films are about twice as hard as amorphous ones. Unfortunately, the mechanical properties of most engineering steels are degraded at temperatures above 250-350 deg. C. This work is focused on using energetic reactive ion bombardment during simultaneous pulsed laser deposition to enhance film crystallization at low temperatures. Alumina films were grown at several background gas pressures and temperatures, with and without Ar ion bombardment. The films were nearly stoichiometric except for depositions in vacuum. Using nitrogen ion bombardment, nitrogen was incorporated into the films and formed the Al-O-N matrix. Nitrogen concentration could be controlled through selection of gas pressure and ion energy. Crystalline Al-O-N films were grown at 330 deg. C with a negative bias voltage to the substrate, and showed improved hardness in comparison to amorphous films.

  1. Investigation on effect of laser shock processing on fatigue crack initiation and its growth in aluminum alloy plate

    International Nuclear Information System (INIS)

    Zhang, X.Q.; Li, H.; Yu, X.L.; Zhou, Y.; Duan, S.W.; Li, S.Z.; Huang, Z.L.; Zuo, L.S.

    2015-01-01

    Highlights: • LSP can greatly delay crack formation. • The micro-crack growing processes and its fracture are showed clearly. • Surface topographies and crack initiation locations are displayed. - Abstract: A series of contrasting experiments were carried out to examine the effects of laser shock processing (LSP) on fatigue properties of slot in 7075-T6 aluminum alloy plate. Both side surfaces of slot were subjected to LSP. The surface topographies were observed and the residual stresses were tested. The treated and the un-treated specimens were pulled by the fatigue cyclic loading respectively. The fatigue crack propagating processes were recorded, and the fatigue fracture microscopic morphologies were analyzed by scanning electron microscope (SEM). Experimental results and analyses show that LSP induces micro-dent on surface and squeezes the compressive residual stresses into surface layer of specimen. It can remarkably delay the micro-crack formation, and transfer the location of fatigue crack initiation from top surface to sub-surface. The spacing of fatigue striations on the treated specimen fatigue fracture obviously decreases. Therefore, the fatigue life of specimen after LSP treatment significantly increases

  2. Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

    Science.gov (United States)

    Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

    2015-09-02

    We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

  3. Laser Shock Peening on Microwave Sintered Aluminum Alloy Nanocompo-Sites

    Directory of Open Access Journals (Sweden)

    S. Prabhakaran

    2018-04-01

    Full Text Available The current work focusses on low energy laser shock peening (LSP on graphene (0.4 wt % – AA 2900 nano-composite fabricated through powder metallurgy (PM technique. The added graphene serves the pinning effect and blocks the grain growth in the composite. Further, LSP has been carried out on the developed composites. As a consequence, LSP contributed the additional grain refinement effectively to the nanocomposites leading to large texture strengthening. Improvement in the hardness and tensile strength achieved with the addition of graphene and further improvement due to LSP process is achieved for the prepared nanocomposites.

  4. Laser-produced aluminum plasma expansion inside a plastic plasma envelope

    Czech Academy of Sciences Publication Activity Database

    Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Parys, P.; Renner, Oldřich; Gus´kov, S.Y.; Demchenko, N. N.; Ullschmied, Jiří; Krouský, Eduard; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří

    2012-01-01

    Roč. 19, č. 9 (2012), s. 1-8 ISSN 1070-664X R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA ČR GAP205/10/0814 Grant - others:7FP LASERLAB-EUROPE(XE) 228334 Program:FP7 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser-mater interaction * plasma jets production * x-ray spectroscopy * particle plasma diagnosis * ion charge density * plasma temperature Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.376, year: 2012

  5. High excitation of the species in nitrogen–aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

    International Nuclear Information System (INIS)

    Liang, Peipei; Li, Yanli; Cai, Hua; You, Qinghu; Yang, Xu; Huang, Feiling; Sun, Jian; Xu, Ning; Wu, Jiada

    2014-01-01

    A reactive nitrogen–aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N 2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N 2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N 2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen–aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis. - Highlights: • ECR discharge and pulsed laser ablation generate highly excited ECR–PLA plasma. • The expansion of PLA plasma results in excitation enhancement of ECR plasma species. • The ECR plasma leads to excitation prolongation of PLA plasma species. • The ECR–PLA plasma emits strong emissions from a variety of excited species. • The ECR–PLA plasma maintains high vibrational–rotational temperatures for a long time

  6. Study of Internal Channel Surface Roughnesses Manufactured by Selective Laser Melting in Aluminum and Titanium Alloys

    Science.gov (United States)

    Pakkanen, Jukka; Calignano, Flaviana; Trevisan, Francesco; Lorusso, Massimo; Ambrosio, Elisa Paola; Manfredi, Diego; Fino, Paolo

    2016-08-01

    Interest in additive manufacturing (AM) has gained considerable impetus over the past decade. One of the driving factors for AM success is the ability to create unique designs with intrinsic characteristics as, e.g., internal channels used for hydraulic components, cooling channels, and heat exchangers. However, a couple of the main problems in internal channels manufactured by AM technologies are the high surface roughness obtained and the distortion of the channel shape. There is still much to understand in these design aspects. In this study, a cylindrical geometry for internal channels to be built with different angles with respect to the building plane in AlSi10Mg and Ti6Al4V alloys by selective laser melting was considered. The internal surfaces of the channels produced in both materials were analyzed by means of a surface roughness tester and by optical and electron microscopy to evaluate the effects of the material and design choices.

  7. Dry metal forming of high alloy steel using laser generated aluminum bronze tools

    Directory of Open Access Journals (Sweden)

    Freiße Hannes

    2015-01-01

    Full Text Available Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the tool and sheet material. The potential to generate tailored tribological systems for dry metal forming could be shown within the investigations by using different material combinations and by applying different laser cladding process parameters. Furthermore, the feasibility of additive manufacturing of a deep drawing tool was demonstrated. The tool was successfully applied to form circular cups in a dry metal forming process.

  8. Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

    Science.gov (United States)

    Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

    2007-05-01

    We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5nm at variable laser pulse widths between 200ps and 25ns. The plasma target was a 30μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25ns at an intensity of 5×1010W/cm2.

  9. Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

    International Nuclear Information System (INIS)

    Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

    2007-01-01

    We demonstrated efficacy of a CO 2 -laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5 nm at variable laser pulse widths between 200 ps and 25 ns. The plasma target was a 30 μm liquid xenon microjet. To ensure the optimum coupling of CO 2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5 nm EUV emission for different pulse widths of the CO 2 laser. A maximum CE of 0.6% was obtained for a CO 2 laser pulse width of 25 ns at an intensity of 5x10 10 W/cm 2

  10. Modelling of fluid flow phenomenon in laser+GMAW hybrid welding of aluminum alloy considering three phase coupling and arc plasma shear stress

    Science.gov (United States)

    Xu, Guoxiang; Li, Pengfei; Cao, Qingnan; Hu, Qingxian; Gu, Xiaoyan; Du, Baoshuai

    2018-03-01

    The present study aims to develop a unified three dimensional numerical model for fiber laser+GMAW hybrid welding, which is used to study the fluid flow phenomena in hybrid welding of aluminum alloy and the influence of laser power on weld pool dynamic behavior. This model takes into account the coupling of gas, liquid and metal phases. Laser heat input is described using a cone heat source model with changing peak power density, its height being determined based on the keyhole size. Arc heat input is modeled as a double ellipsoid heat source. The arc plasma flow and droplet transfer are simulated through the two simplified models. The temperature and velocity fields for different laser powers are calculated. The computed results are in general agreement with the experimental data. Both the peak and average values of fluid flow velocity during hybrid welding are much higher than those of GMAW. At a low level of laser power, both the arc force and droplet impingement force play a relatively large role on fluid flow in the hybrid welding. Keyhole depth always oscillates within a range. With an increase in laser power, the weld pool behavior becomes more complex. An anti-clockwise vortex is generated and the stability of keyhole depth is improved. Besides, the effects of laser power on different driving forces of fluid flow in weld pool are also discussed.

  11. A Pilot Study of Skin Resurfacing Using the 2,790-nm Erbium:YSGG Laser System.

    Science.gov (United States)

    Rhie, Jong Won; Shim, Jeong Su; Choi, Won Seok

    2015-01-01

    The erbium:yttrium scandium gallium garnet (Er:YSGG) laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide (CO2) laser and the erbium-doped yttrium aluminum garnet (Er:YAG) laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser. Twenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera) twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured. Study subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment. The 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color.

  12. A Pilot Study of Skin Resurfacing Using the 2,790-nm Erbium:YSGG Laser System

    Directory of Open Access Journals (Sweden)

    Jong Won Rhie

    2015-01-01

    Full Text Available BackgroundThe erbium:yttrium scandium gallium garnet (Er:YSGG laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide (CO2 laser and the erbium-doped yttrium aluminum garnet (Er:YAG laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser.MethodsTwenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured.ResultsStudy subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment.ConclusionsThe 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color.

  13. Temporal and spatial dynamics of laser-induced aluminum plasma in argon background at atmospheric pressure: Interplay with the ambient gas

    International Nuclear Information System (INIS)

    Ma, Q.L.; Motto-Ros, V.; Lei, W.Q.; Boueri, M.; Bai, X.S.; Zheng, L.J.; Zeng, H.P.; Yu, J.

    2010-01-01

    Laser ablation in background gas implies supplementary complexities with respect to what happens in the vacuum. It is however essential to understand in detail the involved mechanisms for a number of applications requiring the ablation to be performed in an ambient gas at relative high pressure, such as pulsed-laser deposition, or laser-induced breakdown spectroscopy. In this paper, the expansion of a vapor plume ablated from an aluminum target into an argon gas at atmospheric pressure is experimentally investigated using time- and space-resolved emission spectroscopy. The obtained results provide a detailed description of the interplay between the vapor and the gas. The electron density, the temperature and the number densities (and therefore the partial pressures) of aluminum vapor and argon gas have been measured in and surrounding the vapor plume. Our observations show a confinement of the vapor plume by the gas, which is expected as predicted by the usual hydrodynamics models. The result is a plasma core with quite uniform distributions in electron density, temperature and number densities. Such plasma core presents an ideal emission source for spectroscopic applications. It is however evidenced by our observations that a large amount of argon is mixed into the aluminum plume in the plasma core, which invalidates in the experimental conditions that we used, the hydrodynamic 'piston' model where the background gas is pushed out by the shock wave surrounding the vapor plume. Instead, other mechanisms such as laser-supported detonation wave should play important roles in the early stage of the expansion of the plasma for the determination of its morphology at longer delays.

  14. Carbon dioxide laser versus erbium:YAG laser in treatment of epidermal verrucous nevus: a comparative randomized clinical study.

    Science.gov (United States)

    Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi

    2017-08-01

    A verrucous epidermal nevus (VEN) is a skin disorder that has been treated using different treatment modalities with varying results. Ablative lasers such as carbon dioxide laser (CO 2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) laser have been considered as the gold standard for the treatment of epidermal nevi. To evaluate and compare the efficacy, postoperative wound healing and side effects of pulsed CO 2 laser and Er:YAG laser for the treatment of verrucous epidermal nevi. Twenty patients with localized VEN were randomly divided into two groups. Group 1 was administered CO 2 laser and group 2 underwent Er:YAG laser treatment. A blinded physician evaluated the photographs and dermoscopic photomicrographs for the efficacy and possible side effects. All patients received one treatment session and were followed up over a 6-month period. Both lasers induced noticeable clinical improvement, but there were no significant differences between two lasers in treatment response, patient satisfaction, duration of erythema and side effects. The average time to re-epithelialization was 13.5 days with CO 2 and 7.9 days with Er:YAG laser (plaser group and no lesional recurrence was detected in CO 2 laser group since treatment. Apart from re-epithelialization, both lasers showed equivalent outcomes with respect to treatment response, patient satisfaction, side effects and complications.

  15. Polycrystalline magnetic garnet films comprising weakly coupled crystallites for piezoelectrically-driven magneto-optic spatial light modulators

    Energy Technology Data Exchange (ETDEWEB)

    Mito, S.; Sakurai, H.; Takagi, H.; Inoue, M. [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Baryshev, A. V. [Electronics-Inspired Interdisciplinary Research Institute Toyohashi, Aichi 441-8580 (Japan); Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation)

    2012-04-01

    We have investigated the magnetization process of the polycrystalline magnetic garnet films in order to determine the most suitable composition of garnet films for piezoelectrically-driven magneto-optic spatial light modulators (MOSLMs). For experiment, the bismuth-dysprosium-aluminum-substituted yttrium iron (Bi{sub 1.3}Dy{sub 0.7}Y{sub 1.0}Fe{sub 3.1}Al{sub 1.9}O{sub 12}) garnet films were deposited by an RF magnetron sputter and annealed at 700 deg. C in air. The annealing time was varied in a range of several minutes to control the grain size. The saturation magnetization, the remanent magnetization and the composition of the fabricated garnet films slightly changed versus the annealing time. Experiments showed that the coercivity and the grain size increased at longer annealing; the coercivity was larger for films with bigger grains. This work shows that garnet films with smaller coercivity are most suitable for controlling the magnetization of garnet and, correspondingly, the magneto-optical rotation of MOSLM pixels driven by piezoelectrics.

  16. Dislocation polymorphism transformation of 6061-T651 aluminum alloy processed by laser shock processing: Effect of tempering at the elevated temperatures

    International Nuclear Information System (INIS)

    Ren, X.D.; Ruan, L.; Yuan, S.Q.; Ren, N.F.; Zheng, L.M.; Zhan, Q.B.; Zhou, J.Z.; Yang, H.M.; Wang, Y.; Dai, F.Z.

    2013-01-01

    The effects of tempering on surface topography and dislocation configuration of 6061-T651 aluminum alloy by laser shock processing (LSP) were investigated at the elevated temperatures. Surface topography and surface roughness were tested by a Surfcom 130A-Monochrome surface rough-meter. Morphologies of precipitated phases were monitored by scanning electron microscopy (SEM), and the dislocation configurations of samples after LSP were characterized by transmission electron microscope (TEM). The results showed that LSP had a beneficial effect on micro-hardness at elevated temperature. There was a little change of the surface roughness as subjected to LSP. The main strengthening mechanism of micro-hardness was dislocation strengthening and fine grain strengthening, and precipitated phase strengthening was the main strengthening mechanism at elevated temperature. “Dislocation polymorphism transformation” (DPT) effect was affirmed at elevated temperature, and the elevated temperature was principal element for inducing the DPT effect of 6061-T651 aluminum alloy by LSP

  17. Raman spectroscopy of garnet-group minerals

    Science.gov (United States)

    Mingsheng, P.; Mao, Ho-kwang; Dien, L.; Chao, E.C.T.

    1994-01-01

    The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

  18. Spectral and luminescence properties of Cr(3+) ad Nd(3+) ions in gallium garnet crystals

    Science.gov (United States)

    Denisov, A. L.; Ostroumov, V. G.; Saidov, Z. S.; Smirnov, V. A.; Shcherbakov, I. A.

    1986-01-01

    The effective peak stimulated-emission cross section of chromium-doped gadolinium-scandium-gallium garnets (GSGG) has been determined to be 8.5 x 10 to the -21st sq cm at room temperature. The values of the energy-gap Delta E(2E-4T2) chromim fluorescence lifetime and the chromium to neodymium energy-transfer parameter C(DA) (Cr-Nd) are determined for several gallium garnets. Temperature-dependent absorption and luminescence spectra of neodymium-doped GGG and GSGG are reported and discussed in the context of their use as laser materials.

  19. Garnet peridotite found in the Greater Antilles

    Science.gov (United States)

    Abbott, Richard N., Jr.; Draper, Grenville; Keshav, Shantanu

    Although Alpine peridotites are relatively common in collisional orogenic zones, garnet-bearing peridotites are rare and only associated with high pressure/ultra-high pressure or temperature (HP/UHP or T) terranes [Brueckner and Medaris, 2000; Medaris, 1999]. Until recently all reported occurrences of Alpine-type garnet peridotites and HP/UHP terranes were in Eurasia and Africa, with one occurrence in the Seward Peninsula, Alaska [Till, 1981;Lieberman and Till, 1987]. Now a new Alpine-type garnet peridotite locality has been discovered in the Caribbean island of Hispaniola. This discovery is the second of its kind in the Americas.

  20. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  1. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    International Nuclear Information System (INIS)

    Kikuchi, T.; Takahashi, H.; Maruko, T.

    2007-01-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθ stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 μm line width were obtained successfully

  2. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan)]. E-mail: kiku@elechem1-mc.eng.hokudai.ac.jp; Takahashi, H. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan); Maruko, T. [Furuya Metal Co. Ltd., R and D Group, Shimodate Daiichi Kogyodanchi 1915, Morisoejima, Chikusei, Ibaraki (Japan)

    2007-02-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZ{theta} stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 {mu}m line width were obtained successfully.

  3. Effect of Mg and Cu on mechanical properties of high-strength welded joints of aluminum alloys obtained by laser welding

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.

    2017-09-01

    Results of experimental investigations of welded joints of high-strength aluminum-lithium alloys of the Al-Cu-Li and Al-Mg-Li systems are reported. The welded joints are obtained by means of laser welding and are subjected to various types of processing for obtaining high-strength welded joints. A microstructural analysis is performed. The phase composition and mechanical properties of the welded joints before and after heat treatment are studied. It is found that combined heat treatment of the welded joint (annealing, quenching, and artificial ageing) increases the joint strength, but appreciably decreases the alloy strength outside the region thermally affected by the welding process.

  4. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    International Nuclear Information System (INIS)

    Yousef, Adel K. M.; Taha, Ziad A.; Shehab, Abeer A.

    2011-01-01

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  5. Evaluation of Optical Depths and Self-Absorption of Strontium and Aluminum Emission Lines in Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Alfarraj, Bader A; Bhatt, Chet R; Yueh, Fang Yu; Singh, Jagdish P

    2017-04-01

    Laser-induced breakdown spectroscopy (LIBS) is a widely used laser spectroscopic technique in various fields, such as material science, forensic science, biological science, and the chemical and pharmaceutical industries. In most LIBS work, the analysis is performed using radiative transitions from atomic emissions. In this study, the plasma temperature and the product [Formula: see text] (the number density N and the absorption path length [Formula: see text]) were determined to evaluate the optical depths and the self-absorption of Sr and Al lines. A binary mixture of strontium nitrate and aluminum oxide was used as a sample, consisting of variety of different concentrations in powder form. Laser-induced breakdown spectroscopy spectra were collected by varying various parameters, such as laser energy, gate delay time, and gate width time to optimize the LIBS signals. Atomic emission from Sr and Al lines, as observed in the LIBS spectra of different sample compositions, was used to characterize the laser induced plasma and evaluate the optical depths and self-absorption of LIBS.

  6. Quantitative analysis for the determination of aluminum percentage and detonation performance of aluminized plastic bonded explosives by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rezaei, A. H.; Keshavarz, M. H.; Kavosh Tehrani, M.; Darbani, S. M. R.

    2018-06-01

    The aluminized plastic-bonded explosive (PBX) is a composite material in which solid explosive particles are dispersed in a polymer matrix, which includes three major components, i.e. polymeric binder, metal fuel (aluminum) and nitramine explosive. This work introduces a new method on the basis of the laser-induced breakdown spectroscopy (LIBS) technique in air and argon atmospheres to investigate the determination of aluminum content and detonation performance of aluminized PBXs. Plasma emissions of aluminized PBXs are recorded where atomic lines of Al, C and H as well as molecular bands of AlO and CN are identified. The experimental results demonstrate that a good discrimination and separation between the aluminized PBXs is possible using LIBS and principle component analysis, although they have similar atomic composition. Relative intensity of the AlO/Al is used to determine aluminum percentage of the aluminized PBXs. The obtained quantitative calibration curve using the relative intensity of the AlO/Al is better than the resulting calibration curve using only the intensity of Al. By using the LIBS method and the measured intensity ratio of CN/C, an Al content of 15% is found to be the optimum value in terms of velocity of detonation of the RDX/Al/HTPB standard samples.

  7. Bouveret's syndrome complicated by distal gallstone ileus after laser lithotropsy using Holmium: YAG laser

    Directory of Open Access Journals (Sweden)

    Rodgers John B

    2002-06-01

    Full Text Available Abstract Background Bouveret's syndrome is an unusual presentation of duodenal obstruction caused by the passage of a large gallstone through a cholecystoduodenal fistula. Endoscopic therapy has been used as first-line treatment, especially in patients with high surgical risk. Case presentation We report a 67-year-old woman who underwent an endoscopic attempt to fragment and retrieve a duodenal stone using a Holmium: Yttrium-Aluminum-Garnet Laser (Ho:YAG which resulted in small bowel obstruction. The patient successfully underwent enterolithotomy without cholecystectomy or closure of the fistula. Conclusion We conclude that, distal gallstone obstruction, due to migration of partially fragmented stones, can occur as a possible complication of laser lithotripsy treatment of Bouveret's syndrome and might require urgent enterolithotomy.

  8. Modeling skin cooling using optical windows and cryogens during laser induced hyperthermia in a multilayer vascularized tissue

    International Nuclear Information System (INIS)

    Singh, Rupesh; Das, Koushik; Okajima, Junnosuke; Maruyama, Shigenao; Mishra, Subhash C.

    2015-01-01

    This article deals with the spatial and the temporal evolution of tissue temperature during skin surface cooled laser induced hyperthermia. Three different skin surface cooling methodologies viz., optical window contact cooling, cryogenic spray cooling and cryogen cooled optical window contact cooling are considered. Sapphire, yttrium aluminum garnet, lithium tantalate, and magnesium oxide doped lithium niobate are the considered optical windows. The cryogens considered are liquid CO_2 and R1234yf. Heat transfer in the multilayer skin tissue embedded with thermally significant blood vessels pairs is modeled using the Pennes and Weinbaum–Jiji bioheat equations. Weinbaum–Jiji bioheat equation is used for the vascularized tissue. Laser transport in the tissue is modeled using the radiative transfer equation. Axial and radial (skin surface) temperature distributions for different combinations of optical windows and cryogens are analyzed. Liquid CO_2 cooled yttrium aluminum garnet is found to be the best surface cooling mechanism. - Highlights: • Skin surface cooled laser induced hyperthermia is studied. • A multi-layer 2-D cylindrical tissue geometry is considered. • Both Pennes and Weinbaum–Jiji bioheat models are considered. • Laser transport in the tissue is modeled using discrete ordinate method. • Results for 4 optical windows and 2 cryogens for skin cooling are presented.

  9. Epitaxial Garnets and Hexagonal Ferrites.

    Science.gov (United States)

    1982-04-20

    guide growth of the epitaxial YIG films. Aluminum or gallium substitu- tions for iron were used in combination with lanthanum substitutions for yttrium... gallate spinel sub- strates. There was no difficulty with nucleation in the melt and film quality appeared to be similar to that observed previously...hexagonal ferrites. We succeeded in growing the M-type lead hexaferrite (magnetoplumbite) on gallate spinel substrates. We found that the PbO-based

  10. Laser coating of aluminum alloy EN AW 6082-T651 with TiB2 and TiC: Microstructure and mechanical properties

    Science.gov (United States)

    Ravnikar, Dunja; Dahotre, Narendra B.; Grum, Janez

    2013-10-01

    This paper deals with laser coating of ceramics by deposition of a precursor powder mixture of TiB2-TiC-Al on an EN AW 6082-T651 aluminum alloy. The resulting coating was studied by means of a microstructural and mechanical analysis. The coating has with TiC and TiB2 particles of various shapes and sizes embedded in an Al matrix, as well as being adherent and free of cracks with an average porosity lower than 2%. Microhardness in the coating is 40% higher than the uncoated alloy, while the microhardness in the laser melt zone and heat-affected zone dropped significantly. The wear test showed a great improvement in terms of the mass lost after the 30 min test. The three-point bending test was used to determine the flexural properties of the coated aluminum alloy. Higher content of TiB2 in ceramic components increases the flexural strength of the coated specimens, delaying the occurrence of the first crack in the coating or the occurrence of delamination. The measurements of residual stresses confirmed the presence of favorable compressive residual stresses in the surface coating. With depth, these stresses become tensile.

  11. Nonablative laser treatment of facial rhytides

    Science.gov (United States)

    Lask, Gary P.; Lee, Patrick K.; Seyfzadeh, Manouchehr; Nelson, J. Stuart; Milner, Thomas E.; Anvari, Bahman; Dave, Digant P.; Geronemus, Roy G.; Bernstein, Leonard J.; Mittelman, Harry; Ridener, Laurie A.; Coulson, Walter F.; Sand, Bruce; Baumgarder, Jon; Hennings, David R.; Menefee, Richard F.; Berry, Michael J.

    1997-05-01

    The purpose of this study is to evaluate the safety and effectiveness of the New Star Model 130 neodymium:yttrium aluminum garnet (Nd:YAG) laser system for nonablative laser treatment of facial rhytides (e.g., periorbital wrinkles). Facial rhytides are treated with 1.32 micrometer wavelength laser light delivered through a fiberoptic handpiece into a 5 mm diameter spot using three 300 microsecond duration pulses at 100 Hz pulse repetition frequency and pulse radiant exposures extending up to 12 J/cm2. Dynamic cooling is used to cool the epidermis selectively prior to laser treatment; animal histology experiments confirm that dynamic cooling combined with nonablative laser heating protects the epidermis and selectively injures the dermis. In the human clinical study, immediately post-treatment, treated sites exhibit mild erythema and, in a few cases, edema or small blisters. There are no long-term complications such as marked dyspigmentation and persistent erythema that are commonly observed following ablative laser skin resurfacing. Preliminary results indicate that the severity of facial rhytides has been reduced, but long-term follow-up examinations are needed to quantify the reduction. The mechanism of action of this nonablative laser treatment modality may involve dermal wound healing that leads to long- term synthesis of new collagen and extracellular matrix material.

  12. High-power continuous wave and passively Q-switched laser operations of a Nd:GGG crystal

    International Nuclear Information System (INIS)

    Qin, L J; Tang, D Y; Xie, G Q; Dong, C M; Jia, Z T; Tao, X T

    2008-01-01

    We report on the continuous wave (CW) and passive Q-switching performance of a high-power diode-pumped Nd:GGG laser. A CW output power of 7.20 W was obtained under an absorbed pump power of 14.97 W, which gives a slop efficiency of 52.7%. With a Cr 4+ doped yttrium aluminum garnet crystal as the saturable absorber, the shortest passively Q-switched pulse width, largest pulse energy, and highest peak power achieved were 7.7 ns, 126.25 μJ, and 15.5 kW, respectively

  13. Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source.

    Science.gov (United States)

    Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

    2007-03-01

    A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 microm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2 x 10(11) Wcm(2) with a spot diameter of 175 microm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal.

  14. Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source

    Science.gov (United States)

    Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

    2007-03-01

    A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 μm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2×1011 W/cm2 with a spot diameter of 175 μm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal.

  15. Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source

    International Nuclear Information System (INIS)

    Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

    2007-01-01

    A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 μm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2x10 11 W/cm 2 with a spot diameter of 175 μm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal

  16. Magnetodielectric coupling in multiferroic holmium iron garnets

    International Nuclear Information System (INIS)

    Malar Selvi, M.; Chakraborty, Deepannita; Venkateswaran, C.

    2017-01-01

    Single phase magneto-electric multiferroics require a large magnetic or electric field for producing magneto-electric (ME) and magnetodielectric (MD) effects. For utilizing these effects in devices investigations on the room temperature and low field MD studies are necessary. Recently, efforts have been largely devoted to the investigation of rare earth iron garnets. In the physical method, the preparation of rare earth iron garnet requires high sintering temperature and processing time. To solve these problems, ball milling assisted microwave sintering technique is used to prepare nanocrystalline holmium iron garnets (Ho_3Fe_5O_1_2). Magnetic and dielectric properties of the prepared sample are investigated. These properties get enhanced in nanocrystalline form when compared to the bulk. The MD coupling of the prepared sample is evident from the anomaly in the temperature dependent dielectric constant plot and the ME coupling susceptibility is derived from the room temperature MD measurements. - Highlights: • Formation of single phase Holmium iron garnet reported. • Ball milling assisted microwave sintering reduces the sintering temperature and time. • Holmium iron garnet shows enhanced magnetic and dielectric properties. • Pyromagnetic and pyroelectric measurements confirm the magnetoelectric coupling. • Room temperature magnetodielectric measurements show the nonlinear behaviour.

  17. Synthesis of crystalline Ce-activated garnet phosphor powders and technique to characterize their scintillation light yield

    Science.gov (United States)

    Gordienko, E.; Fedorov, A.; Radiuk, E.; Mechinsky, V.; Dosovitskiy, G.; Vashchenkova, E.; Kuznetsova, D.; Retivov, V.; Dosovitskiy, A.; Korjik, M.; Sandu, R.

    2018-04-01

    This work reports on a process of preparation of garnet phosphor powders and a technique for light yield evaluation of strongly light scattering samples. Powders of scintillation compounds could be used as individual materials or as samples for express tests of scintillation properties. However, estimation of their light yield (LY) is complicated by strong light scattering of this kind of materials. Ce3+-activated yttrium-aluminum and gallium-gadolinium-aluminum garnet phosphor powders, Y3Al5O12 (YAG:Ce) and Gd3Ga3Al2O12 (GGAG:Ce), were obtained using a modified coprecipitation technique. Ga tends to residue in mother liquor in ammonia media, but the modification allows to avoid the loss of components. We propose an approach for sample preparation and LY measurement setup with alpha particles excitation, allowing to decrease light scattering influence and to estimate a light yield of powder samples. This approach is used to evaluate the obtained powders.

  18. Improving the Performance of Gold-Nanoparticle-Doped Solid-State Dye Laser Using Thermal Conversion Effect

    Science.gov (United States)

    An, N. T. M.; Lien, N. T. H.; Hoang, N. D.; Hoa, D. Q.

    2018-04-01

    Energy transfer between spherical gold nanoparticles with size of more than 15 nm and molecules of organic dye 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H-pyran (DCM) has been studied. Such radiative energy transfer led to high local temperature, giving rise to a bleaching effect that resulted in rapid degradation of the laser medium. Gold nanoparticles were dispersed at concentrations from 5 × 109 particles/mL to 5 × 1010 particles/mL in DCM polymethylmethacrylate polymer using a radical polymerization process with 2,2'-azobis(isobutyronitrile) (AIBN) as initiator. Using the fast thermoelectric cooling method, the laser medium stability was significantly improved. The output stability of a distributed feedback dye laser pumped by second-harmonic generation from a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was investigated. Moreover, bidirectional energy transfer between gold nanoparticles and dye molecules was observed.

  19. Aluminum Hydroxide

    Science.gov (United States)

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  20. Peak metamorphic temperatures from cation diffusion zoning in garnet

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik; Mezger, Klaus

    2013-01-01

    ) to develop a tool that uses the diffusion zoning of these cations in garnet to constrain peak temperature conditions for garnet-bearing rocks. The thermometric approach was externally tested by applying it to garnet crystals from various metamorphic terranes worldwide and comparing the results to published...

  1. Systematic hardness measurements on some rare earth garnet ...

    Indian Academy of Sciences (India)

    Unknown

    Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium ... syan (1997) has quoted a single value for Gd3Sc2Ga3O12. In the present study measurements have ... small and within the limits of experimental error. There- fore, where pure garnet crystals ...

  2. Simulation of ablation and plume dynamics under femtosecond double-pulse laser irradiation of aluminum: Comparison of atomistic and continual approaches

    Energy Technology Data Exchange (ETDEWEB)

    Fokin, Vladimir B.; Povarnitsyn, Mikhail E., E-mail: povar@ihed.ras; Levashov, Pavel R.

    2017-02-28

    Highlights: • We model double-pulse laser ablation of aluminum using microscopic and macroscopic approaches. • Both methods show decrease in depth of crater with increasing delay between pulses. • Both methods reveal the plume temperature growth with the increasing delay. • Good agreement between results is a step towards the development of combined model. - Abstract: We elaborated two numerical methods, two-temperature hydrodynamics and hybrid two-temperature molecular dynamics, which take into account basic mechanisms of a metal target response to ultrashort laser irradiation. The model used for the description of the electronic subsystem is identical for both approaches, while the ionic part is defined by an equation of state in hydrodynamics and by an interatomic potential in molecular dynamics. Since the phase diagram of the equation of state and corresponding potential match reasonably well, the dynamics of laser ablation obtained by both methods is quite similar. This correspondence can be considered as a first step towards the development of a self-consistent combined model. Two important processes are highlighted in simulations of double-pulse ablation: (1) the crater depth decrease as a result of recoil flux formation in the nascent plume when the delay between the pulses increases; (2) the plume reheating by the second pulse that gives rise to two- three-fold growth of the electron temperature with the delay varying from 0 to 200 ps.

  3. Dynamics expansion of laser produced plasma with different materials in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rabia Qindeel; Noriah Bte Bidin; Yaacob Mat daud [Laser Technology Laboratory, Physics Department, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)], E-mail: plasmaqindeel@yahoo.com

    2008-12-01

    The dynamics expansion of the plasma generated by laser ablation of different materials has been investigated. The dynamics and confinement of laser generated plasma plumes are expanding across variable magnetic fields. A Q-switched neodymium-doped yttrium aluminum garnet laser with 1064 nm, 8 ns pulse width and 0.125 J laser energy was used to generate plasma that was allowed to expand across variable magnetic within 0.1 - 0.8 T. The expansions of laser-produced plasma of different materials are characterized by using constant laser power. CCD video camera was used to visualize and record the activities in the focal region. The plasma plume length, width and area were measured by using Matrox Inpector 2.1 and video Test 0.5 software. Spectrums of plasma beam from different materials are studied via spectrometer. The results show that the plasma generated by aluminum target is the largest than Brass and copper. The optical radiation from laser generated plasma beam spectrums are obtained in the range of UV to visible light.

  4. Shear Bond Strength of Composite and Ceromer Superstructures to Direct Laser Sintered and Ni-Cr-Based Infrastructures Treated with KTP, Nd:YAG, and Er:YAG Lasers: An Experimental Study.

    Science.gov (United States)

    Gorler, Oguzhan; Hubbezoglu, Ihsan; Ulgey, Melih; Zan, Recai; Guner, Kubra

    2018-04-01

    The aim of this study was to examine the shear bond strength (SBS) of ceromer and nanohybrid composite to direct laser sintered (DLS) Cr-Co and Ni-Cr-based metal infrastructures treated with erbium-doped yttrium aluminum garnet (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), and potassium titanyl phosphate (KTP) laser modalities in in vitro settings. Experimental specimens had four sets (n = 32) including two DLS infrastructures with ceromer and nanohybrid composite superstructures and two Ni-Cr-based infrastructures with ceromer and nanohybrid composite superstructures. Of each infrastructure set, the specimens randomized into four treatment modalities (n = 8): no treatment (controls) and Er:YAG, Nd:YAG, and KTP lasers. The infrastructures were prepared in the final dimensions of 7 × 3 mm. Ceromer and nanohybrid composite was applied to the infrastructures after their surface treatments according to randomization. The SBS of specimens was measured to test the efficacy of surface treatments. Representative scanning electron microscopy (SEM) images after laser treatments were obtained. Overall, in current experimental settings, Nd:YAG, KTP, and Er:YAG lasers, in order of efficacy, are effective to improve the bonding of ceromer and nanohybrid composite to the DLS and Ni-Cr-based infrastructures (p laser is more effective in the DLS/ceromer infrastructures (p laser, as second more effective preparation, is more effective in the DLS/ceromer infrastructures (p laser modalities, in order of success, Nd:YAG, KTP, and Er:YAG, are effective to increase bonding of these structures.

  5. Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

    Science.gov (United States)

    Lorusso, Massimo; Aversa, Alberta; Manfredi, Diego; Calignano, Flaviana; Ambrosio, Elisa Paola; Ugues, Daniele; Pavese, Matteo

    2016-08-01

    Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

  6. Long-Wave Infrared (LWIR) Molecular Laser-Induced Breakdown Spectroscopy (LIBS) Emissions of Thin Solid Explosive Powder Films Deposited on Aluminum Substrates.

    Science.gov (United States)

    Yang, Clayton S-C; Jin, Feng; Trivedi, Sudhir B; Brown, Ei E; Hommerich, Uwe; Tripathi, Ashish; Samuels, Alan C

    2017-04-01

    Thin solid films made of high nitro (NO 2 )/nitrate (NO 3 ) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region. A preliminary assessment of the detection limit for a thin film of RDX on aluminum appears to be much lower than 60 µg/cm 2 . This LWIR LIBS setup is capable of rapidly probing and charactering samples without the need for elaborate sample preparation and also offers the possibility of a simultaneous ultraviolet visible and LWIR LIBS measurement.

  7. Laser amplification of optical images using a CW Nd:YAG amplifier

    International Nuclear Information System (INIS)

    Aman, H

    2013-01-01

    In this paper a scheme for the amplification of optical images is described, using a continuous wave (CW) diode-pumped Nd:YAG (yttrium aluminum garnet) laser module. A passively q-switched end-pumped Nd:YAG laser is used as a pump source, which carries the optical image distribution as an input which is transmitted towards the amplifier at a distance of about ten feet. For amplification, a three-side-pumped CW Nd:YAG laser module is utilized without the cavity mirrors. In this way, optical images are amplified by a factor of 3.2 and imaged at a distance of ten feet with a spatial resolution of 500 μm. (paper)

  8. Multifocal Gastric Neoplasia after Recurrent Laser Therapy for the Watermelon Stomach

    Directory of Open Access Journals (Sweden)

    Charles N Bernstein

    1997-01-01

    Full Text Available Repeated laser therapy has become an accepted therapeutic approach in the treatment of watermelon stomach, and to date no important negative sequelae have been reported. The case of a patient who underwent repeated sessions of neodymium: yttrium aluminum garnet (Nd:YAG laser therapy over a five-year period for the treatment of the watermelon stomach is presented. Postlaser therapy the patient developed deep ulcerations that would heal; however, he ultimately developed a nodular antrum. Random biopsies of antral nodules revealed carcinoma-in-situ. A Billroth I gastrectomy revealed two foci of carcinoma-in-situ/high grade dysplasia and multiple foci of lower grades of dysplasia. This case suggests a possible association between use of laser therapy and development of gastric neoplasia.

  9. Efficient enhancement of bismuth NIR luminescence by aluminum and its mechanism in bismuth doped germanate laser glass

    DEFF Research Database (Denmark)

    Wang, L.P.; Tan, L.L.; Yue, Yuanzheng

    2016-01-01

    As a new member of laser glass family, bismuth-doped glasses have received rising interests due to the application of fiber amplifiers and laser sources in the new spectral range for the next-generation optical communication system. For practical application of the glasses, it must be considered ...

  10. Optimizing laser crater enhanced Raman spectroscopy.

    Science.gov (United States)

    Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

    2018-03-20

    Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

  11. Novel low fluence combination laser treatment of solar lentigines in type III Asian skin

    Directory of Open Access Journals (Sweden)

    Brian Wei Cheng Anthony Tian

    2015-01-01

    Full Text Available Objective: To demonstrate a novel low fluence combination laser technique [Erbium-doped yttrium aluminum garnet (Erb:YAG and neodymium-doped yttrium aluminum garnet (Nd:YAG] to effectively treat solar lentigines in type III Asian skin in a single session. Design: A prospective study. Setting: A Singapore-based clinic. Participants: Five patients (all females were enrolled into the study. The ages ranged 35-60 years; all patients had Fitzpatrick skin type III. Measurements: Photographs were taken at baseline and at 1-month follow-up. These were reviewed by two independent physicians who were blinded to the study. Changes in pigment severity were assessed by a 5-point scale (1: Aggravation of pigment, 2: No change, 3: 25-50% improvement, 4: 51-75% improvement, and 5: 76-100% improvement. Results: All patients received a single treatment session. At 1-month follow-up, a reduction in pigment was observed in all patients. Both physicians′ reports were independently agreeable. All patients scored 5, having >90% improvement in pigment severity. No hypopigmentation, postinflammatory hyperpigmentation (PIH, or recurrence was seen. Conclusion: Low fluence combination laser is effective and safe for clearance of solar lentigines in type III Asian skin.

  12. Thermal conductivity of aluminum nitride ceramics. Waermeleitfaehigkeit von Aluminiumnitrid-Keramik

    Energy Technology Data Exchange (ETDEWEB)

    Ruessel, C.; Hofmann, T.; Limmer, G. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Inst. fuer Werkstoffwissenschaften 3)

    Aluminium nitride ceramics made by the authors, as well as others produced commercially, mostly using yttrium oxide as an additive, were characterized with respect to their phase and chemical composition, their microstructure, and their thermal conductivity. It was shown that conventional ideas, especially with regard to the correlations between thermal conductivity and the oxygen content and the microstructure, could not withstand a critical examination. Instead, a connection can be seen between the oxygen not bound up in yttrium-aluminum garnet and thermal conductivity. Relatively low thermal conductivities were always observed when yttrium-aluminum garnet was present as a grain-boundary phase; in contrast, high values of thermal conductivity were seen when the yttrium-aluminum garnet was present in the form of isolated grains. (orig.).

  13. Optical and magnetic properties of a transparent garnet film for atomic physics experiments

    Directory of Open Access Journals (Sweden)

    Mari Saito

    2016-12-01

    Full Text Available We investigated the optical and magnetic properties of a transparent magnetic garnet with a particular focus on its applications to atomic physics experiments. The garnet film used in this study was a magnetically soft material that was originally designed for a Faraday rotator at optical communication wavelengths in the near infrared region. The film had a thickness of 2.1 μm and a small optical loss at a wavelength of λ=780 nm resonant with Rb atoms. The Faraday effect was also small and, thus, barely affected the polarization of light at λ=780 nm. In contrast, large Faraday rotation angles at shorter wavelengths enabled us to visualize magnetic domains, which were perpendicularly magnetized in alternate directions with a period of 3.6 μm. We confirmed the generation of an evanescent wave on the garnet film, which can be used for the optical observation and manipulation of atoms on the surface of the film. Finally, we demonstrated a magnetic mirror for laser-cooled Rb atoms using the garnet film.

  14. Fusion welding of Fe-added lap joints between AZ31B magnesium alloy and 6061 aluminum alloy by hybrid laser-tungsten inert gas welding technique

    International Nuclear Information System (INIS)

    Qi, Xiao-dong; Liu, Li-ming

    2012-01-01

    Highlights: → Hybrid Laser-TIG fusion welding technique was used for joining Mg to Al alloys. → Laser defocusing amount determined penetration depth inside Al alloy of joints. → The addition of Fe interlayer suppressed Mg-Al intermetallics greatly in joints. → A maximum joint strength with optimum thickness of Fe interlayer was obtained. → Excessive addition of Fe interlayer was adverse for the strength improvement. -- Abstract: AZ31B magnesium alloy and 6061-T6 aluminum alloy were lap joined together with the addition of Fe interlayer by fusion welding of hybrid laser-tungsten inert gas (TIG) technique. The influence of location of laser focal spot (LFS) on joint penetration depth and that of the depth on joint strength were investigated. The results showed that when the LFS was just on the surface of Al plate, the deepest penetration could be obtained, which contributed to the improvement of shear strength of Fe-added joints, but not to the elevation of the strength of Mg/Al direct joints. The addition of Fe interlayer suppressed massive production of Mg-Al intermetallics but produced Fe-Al intermetallics in the fusion zone of the joints, whose micro-hardness was extremely high and was also adverse for the enhancement of joint shear strength. The effect of Fe-interlayer thickness on the joint shear strength was also examined, and the maximum shear strength of Fe-added joint could achieve 100 MPa with 0.13 mm thick Fe interlayer. The fracture modes of 0.07 and 0.13 mm Fe-interlayer-added joints were both quasi-cleavage, while those of direct and 0.22 mm interlayer-added joints were completely cleavage. The theoretical shear strength of the Fe-added joints was also discussed.

  15. A model for self-defocusing in laser drilling of polymeric materials

    International Nuclear Information System (INIS)

    Zhang Chong; Quick, Nathaniel R.; Kar, Aravinda

    2008-01-01

    A numerical thermal model is presented for laser microvias drilling in multilayer electronic substrates with Nd:YAG (YAG denotes yttrium aluminum garnet) and CO 2 lasers. Such substrates have different optical properties such as the refractive index and absorption coefficient at these two laser wavelengths, resulting in different drilling mechanisms. Since the skin depth of the polymer is large for both the lasers, volumetric heating is considered in the model. As soon as a small cavity is formed during the drilling process, the concave curvature of the drilling front acts as a concave lens that diverges the incident laser beam. This self-defocusing effect can greatly reduce the drilling speed as predicted by the model. This effect makes the refractive index of the substrate at different wavelengths an important parameter for laser drilling. The model was used to calculate the laser ablation thresholds which were found to be 8 and 56 J/cm 2 for the CO 2 and Nd:YAG lasers respectively. Due to the expulsion of materials because of high internal pressures in the case of Nd:YAG laser microvia drilling, the ablation threshold may be far below the calculated value. A particular laser beam shape, such as pitch fork, was found to drill better holes than the Gaussian beam

  16. Laser triggering of a 500-kV gas-filled switch: A parametric study

    International Nuclear Information System (INIS)

    Woodworth, J.R.; Hargis, P.J. Jr.; Pitchford, L.C.; Hamil, R.A.

    1984-01-01

    We have investigated neodymium: yttrium aluminum garnet (Nd:YAG) laser triggering of a 500-kV, SF 6 -insulated gas switch for a range of laser parameters. Laser wavelengths of 266 nm and 1064 nm with nominal pulse lengths of 2- and 4-nsec full width at half maximum (FWHM) were used to trigger the switch. The switch was triggered by focusing the laser to form a breakdown arc in the gas between the electrodes. Subnanosecond jitter in the operation of the switch was obtained for 266-nm laser pulse energies as low as 5 mJ. Results obtained with the Nd:YAG laser are compared to earlier data in which the switch was triggered with a krypton-fluoride laser operating at 248 nm with a pulse length of 20-nsec FWHM. Our experimental results show that ultraviolet laser triggering gives results which are a dramatic improvement over infrared laser triggering in terms of lower jitter and smaller change in delay time with variations in applied voltage. We also see indications that the optimum laser pulse length is equal to or greater than the closure time of the switch

  17. Acute effects of pulsed-laser irradiation on the arterial wall

    Science.gov (United States)

    Nakamura, Fumitaka; Kvasnicka, Jan; Lu, Hanjiang; Geschwind, Herbert J.; Levame, Micheline; Bousbaa, Hassan; Lange, Francoise

    1992-08-01

    Pulsed laser coronary angioplasty with an excimer or a holmium-yttrium-aluminum-garnet (Ho:YAG) laser may become an alternative treatment for patients with coronary artery disease. However, little is known about its acute consequences on the normal arterial wall. This study was designed to examine the acute histologic consequences of these two pulsed lasers on the arterial wall of normal iliac arteries in rabbits. Irradiation with each laser was performed in 15 normal iliac sites on eight male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mJ/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 micrometers , 3/5 Hz, 400 mJ/pulse, and 250 microsecond(s) ec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The sites irradiated with excimer or Ho:YAG laser had the same kinds of histologic features, consisting of exfoliation of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with Ho:YAG laser (p vascular injury.

  18. Laser cladding technology to small diameter pipes

    International Nuclear Information System (INIS)

    Fujimagari, H.; Hagiwara, M.; Kojima, T.

    2000-01-01

    A laser cladding method which produces a highly corrosion-resistant material coating layers (cladding) on the austenitic stainless steel (type 304 SS) pipe inner surface was developed to prevent SCC (stress corrosion cracking) occurrence. This technology is applicable to a narrow and long distance area from operators, because of the good accessibility of the YAG (yttrium-aluminum-garnet) laser beam that can be transmitted through an optical fiber. In this method a mixed paste metallic powder and heating-resistive organic solvent are firstly placed on the inner surface of a small pipe, and then a YAG laser beam transmitted through an optical fiber irradiates to the pasted area. A mixed paste will be melted and form a cladding layer subsequently. A cladding layer shows as excellent corrosion resistance property. This laser cladding (LC) method had already applied to several domestic nuclear power plants and had obtained a good reputation. This report introduces the outline of laser cladding technology, the developed equipment for practical application in the field, and the circumstance in actual plant application. (orig.)

  19. Lithium-aluminum-zinc phosphate glasses activated with Tb3+ and Tb3+/Eu3+ for green laser medium, reddish-orange and white phosphor applications

    Science.gov (United States)

    Francisco-Rodriguez, H. I.; Lira, A.; Soriano-Romero, O.; Meza-Rocha, A. N.; Bordignon, S.; Speghini, A.; Lozada-Morales, R.; Caldiño, U.

    2018-05-01

    A spectroscopic analysis of Tb3+ and Tb3+/Eu3+ doped lithium-aluminum-zinc phosphate glasses is performed through their absorbance and photoluminescence spectra, and decay time profiles. Laser parameter values (stimulated emission cross section, effective bandwidth, gain bandwidth and optical gain) were obtained for the terbium 5D4 → 7F5 green emission from the Tb3+ singly-doped glass (LAZT) excited at 350 nm to judge the suitability of the glass phosphor for fiber lasers. A quantum yield of (47.68 ± 0.49)% was measured for the 5D4 level luminescence. Upon 350 nm excitation the LAZT glass phosphor emits green light with a color purity of 65.6% and chromaticity coordinates (0.285, 0.585) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. The Tb3+/Eu3+codoped glass emission color can be tuned from reddish-orange of 1865 K upon 318 nm excitation to warm white of 3599 K and neutral white of 4049 K upon 359 and 340 nm excitations, respectively. Upon Tb3+ excitation at 340 nm Eu3+ is sensitized by Tb3+ through a non-radiative energy transfer with an efficiency of 0.23-0.26. An electric dipole-dipole interaction might be the dominant mechanism in the Tb3+ to Eu3+ energy transfer taking place into Tb3+ - Eu3+ clusters.

  20. Laser assisted drug delivery: a review of an evolving technology.

    Science.gov (United States)

    Sklar, Lindsay R; Burnett, Christopher T; Waibel, Jill S; Moy, Ronald L; Ozog, David M

    2014-04-01

    Topically applied drugs have a relatively low cutaneous bioavailability. This article reviews the existing applications of laser assisted drug delivery, a means by which the permeation of topically applied agents can be enhanced into the skin. The existing literature suggests that lasers are a safe and effective means of enhancing the delivery of topically applied agents through the skin. The types of lasers most commonly studied in regards to drug delivery are the carbon dioxide (CO2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) lasers. Both conventional ablative and fractional ablative modalities have been utilized and are summarized herein. The majority of the existing studies on laser assisted drug delivery have been performed on animal models and additional human studies are needed. Laser assisted drug delivery is an evolving technology with potentially broad clinical applications. Multiple studies demonstrate that laser pretreatment of the skin can increase the permeability and depth of penetration of topically applied drug molecules for both local cutaneous and systemic applications. © 2014 Wiley Periodicals, Inc.

  1. Laser application in tracheobronchial tumors

    Science.gov (United States)

    Rau, B. Krishna; Krishna, Sharon

    2004-09-01

    Ninety three patients with obstructing tracheobronchial tumors were treated with Neodymium: Yttrium - Aluminum - Garnet (Nd:YAG) laser photocoagulation over a period of six years. There were sixty seven Males and 26 Females with a mean age of 44.3 years (range 6- 79 years). 21 benign and 72 malignant lesions were treated with a total 212 sessions of laser photocoagulation (mean 2.4 sessions). The anatomical distribution of lesions were as follows; larynx 9 (three benign and 6 malignant) trachea 39 (27 benign and 12 malignant) left main bronchus 27 (14 malignant) right main bronchus 24 (14 malignant) and vocal cords - 9 (three malignant). There were 21 patients with squamous cell carcinoma, two adenocarcinomas, one adenoid cystic carcinoma, 7 cases of locally infiltrating tumors from thyroid and esophagus, 6 cases of carcinoid tumor and 16 benign lesions. Twenty one patients had a tracheostomy tube in place when treatment was started. Eighteen of the 21 patients with tracheostomy were weaned off the tube in a mean of 5.5 days from the start of treatment. Lumen was restored in 31 (79.4%) patients. In the other eight (20.6%), lumen was achieved, but not sustained. Complications included bleeding in three cases which were managed conservatively, two cases of pneumothorax, and four cases of bronchospasm. There were six deaths during the follow up but none attributable to the procedure. Laser photocoagulation offered effective treatment in the majority of patients with obstructing tracheobronchial tumors, with acceptable morbidity.

  2. Effects of striated laser tracks on thermal fatigue resistance of cast iron samples with biomimetic non-smooth surface

    International Nuclear Information System (INIS)

    Tong, Xin; Zhou, Hong; Liu, Min; Dai, Ming-jiang

    2011-01-01

    In order to enhance the thermal fatigue resistance of cast iron materials, the samples with biomimetic non-smooth surface were processed by Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser. With self-controlled thermal fatigue test method, the thermal fatigue resistance of smooth and non-smooth samples was investigated. The effects of striated laser tracks on thermal fatigue resistance were also studied. The results indicated that biomimetic non-smooth surface was benefit for improving thermal fatigue resistance of cast iron sample. The striated non-smooth units formed by laser tracks which were vertical with thermal cracks had the best propagation resistance. The mechanisms behind these influences were discussed, and some schematic drawings were introduced to describe them.

  3. Efficient continuous-wave 1112 nm Nd:YAG laser operation under direct diode pumping at 885 nm

    International Nuclear Information System (INIS)

    Gao, J; Dai, X J; Zhang, L; Wu, X D

    2013-01-01

    We report compact diode-end-pumped continuous-wave laser operation at 1112 nm under 885 nm diode-direct pumping for the first time. On the basis of the R 2 →Y 6 transition in a conventional Nd:YAG (yttrium aluminum garnet) single crystal, the maximum output power of 12.5 W is achieved, with an optical to optical efficiency of 46.6% and a slope efficiency of 52.9%. To the best of our knowledge, this represents the highest output at 1112 nm generated by a diode-end-pumped Nd:YAG laser. Furthermore, it is the highest optical to optical efficiency ever reported for 1112 nm Nd:YAG lasers. The short term power stability is ∼0.32% at 12.0 W output. (letter)

  4. Effect of recording condition on the diffraction efficiency of magnetic hologram with magnetic garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yuichi, E-mail: nakamura@ee.tut.ac.jp; Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, 1-1 Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

    2014-09-14

    A holographic memory has been attracting attention as recording media with high recording density and high data transfer rate. We have studied the magnetic garnets as a rewritable and long life media for magnetic holography. However, since the signal intensity of reconstructed image was relatively low, the effects of recording conditions on the diffraction efficiency of magnetic hologram were investigated with experiments and the numerical simulation using COMSOL multi-physics. The diffraction efficiency tends to decrease as increasing the spatial frequency, and the use of short pulse laser with the pulse width of 50 ps was found to be effective to achieve high diffraction efficiency. This suggests that the formation of clear magnetic fringe similar to interference pattern can be obtained by the use of short pulse laser since undesirable heat diffusion during radiation does not occur. On the other hand, the diffraction efficiency increased as increasing the film thickness up to 3.1 μm but was saturated in the garnet film thicker than 3.1 μm in the case of spatial frequency of 1500 line pair/mm. The numerical simulation showed that the effective depth of magnetic fringe was limited about 1.8 μm irrespective of the garnet film thickness because the fringes were connected by thermal diffusion near the surface of the film, and the effective depth is limited due to this connection of the magnetic fringe. Avoiding this fringe connection, much higher diffraction efficiency will be achieved.

  5. Update on the use of diode laser in the management of benign prostate obstruction in 2014.

    Science.gov (United States)

    Lusuardi, Lukas; Mitterberger, Michael; Hruby, Stephan; Kunit, Thomas; Kloss, Birgit; Engelhardt, Paul F; Sieberer, Manuela; Janetschek, Günter

    2015-04-01

    To determine the status quo in respect of various diode lasers and present the techniques in use, their results and complications. We assess how these compare with transurethral resection of the prostate and other types of laser in randomized controlled trials (RCTs). When adequate RCTs were not available, case studies and reports were evaluated. Laser for the treatment of benign prostatic hyperplasia (BPH) has aroused the interest and curiosity of urologists as well as patients. The patient associates the term laser with a successful and modern procedure. The journey that started with coagulative necrosis of prostatic adenoma based on neodymium: yttrium-aluminum-garnet (Nd:YAG) laser has culminated in endoscopic "enucleation" with holmium laser. Diode laser is being used in urology for about 10 years now. Various techniques have been employed to relieve bladder outlet obstruction due to BPH. The diode laser scenario is marked by a diversity of surgical techniques and wavelengths. We summarize the current published literature in respect of functional results and complications. More randomized controlled studies are needed to determine the position and the ideal technique of diode laser treatment for BPH.

  6. Ultra-low damping in lift-off structured yttrium iron garnet thin films

    Science.gov (United States)

    Krysztofik, A.; Coy, L. E.; Kuświk, P.; Załeski, K.; Głowiński, H.; Dubowik, J.

    2017-11-01

    We show that using maskless photolithography and the lift-off technique, patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping can be accomplished. The films of 70 nm thickness were grown on (001)-oriented gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit high crystalline quality, low surface roughness, and the effective magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as 5 ×10-4. The obtained structures have well-defined sharp edges which along with good structural and magnetic film properties pave a path in the fabrication of high-quality magnonic circuits and oxide-based spintronic devices.

  7. Laser treatment of infantile hemangiomas

    Directory of Open Access Journals (Sweden)

    Michelle Si Ying Ng

    2017-01-01

    Full Text Available Infantile hemangiomas (IHs are the most common benign soft tissue tumor of infancy and childhood. Many patients seek early treatment to halt progression of tumor growth and accelerate regression to achieve quick resolution with good cosmetic outcomes. We reviewed literature through PubMed search on the treatment strategies for IH and share our experience in the field of laser treatment of IH. Treatment strategies for IH include both pharmacological, laser, and surgical interventions depending on the stage and severity of the lesion. Various laser beams have been attempted with varying effects and effectiveness. The 595-nm pulsed dye laser therapy has been most widely utilized owing to its great efficacy but minimal adverse effects. It works by targeting oxyhemoglobin chromophore in blood vessels located within the dermis, causing photothermal damage of these target vessels stimulating quick involution without damaging surrounding healthy skin. It is especially useful in treating ulcerated superficial facial hemangiomas that necessitate rapid healing to avoid unsightly scarring. It has a good safety profile but small risk of epidermal burn, blistering, postinflammatory pigment changes, and scarring remains in those with darker skin types treated with higher fluences and short-pulsed duration. Combination treatment with 1064 nm neodymium-doped yttrium aluminum garnet laser, oral propranolol, and even corticosteroids remains an option, especially in treatment of deep, large, and functionally threatening IH. Careful consideration in consultation with the child's parents given the complexities and potential complications surrounding treatment should always be considered. Laser treatment remains an appropriate treatment for rapidly growing IH in exposed locations at early presentation.

  8. Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers.

    Science.gov (United States)

    Ahn, K J; Kim, B J; Cho, S B

    2017-08-01

    Laser therapy is the treatment of choice in tattoo removal. However, the precise mechanisms of laser-tattoo pigment interactions remain to be evaluated. We evaluated the geometric patterns of laser-tattoo pigment particle interactions using a tattoo pigment-embedded tissue-mimicking (TM) phantom. A Q-switched (QS) neodymium-doped yttrium aluminum garnet laser was used at settings of 532-, 660-, and 1064-nm wavelengths, single-pulse and quick pulse-to-pulse treatment modes, and spot sizes of 4 and 7 mm. Most of the laser-tattoo interactions in the experimental conditions formed cocoon-shaped or oval photothermal and photoacoustic injury zones, which contained fragmented tattoo particles in various sizes depending on the conditions. In addition, a long-pulsed 755-nm alexandrite laser was used at a spot size of 6 mm and pulse widths of 3, 5, and 10 ms. The finer granular pattern of tattoo destruction was observed in TM phantoms treated with 3- and 5-ms pulse durations compared to those treated with a 10-ms pulse. We outlined various patterns of laser-tattoo pigment interactions in a tattoo-embedded TM phantom to predict macroscopic tattoo and surrounding tissue reactions after laser treatment for tattoo removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Concept of the solar-pumped laser-photovoltaics combined system and its application to laser beam power feeding to electric vehicles

    Science.gov (United States)

    Motohiro, Tomoyoshi; Takeda, Yasuhiko; Ito, Hiroshi; Hasegawa, Kazuo; Ikesue, Akio; Ichikawa, Tadashi; Higuchi, Kazuo; Ichiki, Akihisa; Mizuno, Shintaro; Ito, Tadashi; Yamada, Noboru; Nath Luitel, Hom; Kajino, Tsutomu; Terazawa, Hidetaka; Takimoto, Satoshi; Watanabe, Kemmei

    2017-08-01

    We have developed a compact solar-pumped laser (µSPL) employing an off-axis parabolic mirror with an aperture of 76.2 mm diameter and an yttrium aluminum garnet (YAG) ceramic rod of φ1 mm × 10 mm doped with 1% Nd and 0.1% Cr as a laser medium. The laser oscillation wavelength of 1.06 µm, just below the optical absorption edge of Si cells, is suitable for photoelectric conversion with minimal thermal loss. The concept of laser beam power feeding to an electric vehicle equipped with a photovoltaic panel on the roof was proposed by Ueda in 2010, in which the electricity generated by solar panels over the road is utilized to drive a semiconductor laser located on each traffic signal along the road. By substituting this solar-electricity-driven semiconductor laser with a solar-pumped laser, the energy loss of over 50% in converting the solar electricity to a laser beam can be eliminated. The overall feasibility of this system in an urban area such as Tokyo was investigated.

  10. 1.8kW laser diode pumped YAG laser; Shutsuryoku 1.8kW no handotai laser reiki YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Toshiba Corporation, as a participant in Ministry of International Trade and Industry`s `photon measurement and processing technology project` since August, 1997, is engaged in the development of an energy-efficient LD (laser diode) pumped semiconductor YAG (yttrium-aluminum-garnet) laser device to be used for welding and cutting. It is a 5-year project and the goal is a mean output of 10kW and efficiency of 20%. In this article, a simulation program is developed which carries out calculation about element technology items such as the tracking of the beam from the pumping LD and the excitation distribution, temperature distribution, thermal stress distribution, etc., in the YAG rod. An oscillator is constructed, based on the results of the simulation, and it exhibits a world-high class continuous laser performance of a 1.8kW output and 13% efficiency. The record of 13% efficiency is five times higher than that achieved by the conventional lamp-driven YAG laser device. (translated by NEDO)

  11. Saturable absorption of an X-ray free-electron-laser heated solid-density aluminum plasma

    Czech Academy of Sciences Publication Activity Database

    Rackstraw, D.S.; Ciricosta, O.; Vinko, S.M.; Barbrel, B.; Burian, Tomáš; Chalupský, Jaromír; Cho, B.I.; Chung, H.-K.; Dakovski, G.L.; Engelhorn, K.; Hájková, Věra; Heimann, P.; Holmes, M.; Juha, Libor; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J.J.; Zastrau, U.; Wark, J. S.

    2015-01-01

    Roč. 114, č. 1 (2015), "015003-1"-"015003-5" ISSN 0031-9007 R&D Projects: GA ČR(CZ) GA14-29772S; GA MŠk(CZ) LG13029 Grant - others:AVČR(CZ) M100101221 Institutional support: RVO:68378271 Keywords : free electron laser * x-ray * ionization of plasmas Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 7.645, year: 2015

  12. Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

    International Nuclear Information System (INIS)

    Haritha, P.; Linganna, K.; Venkatramu, V.; Martín, I. R.; Monteseguro, V.; Rodríguez-Mendoza, U. R.; Babu, P.; León-Luis, S. F.; Jayasankar, C. K.; Lavín, V.

    2014-01-01

    Trivalent dysprosium-doped Lu 3 Ga 5 O 12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu 3 Ga 5 O 12 nano-garnets have been studied as a function of the optically active Dy 3+ ion concentration and at low temperature. Decay curves for the 4 F 9/2 level of Dy 3+ ion exhibit non-exponential nature for all the Dy 3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy 3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy 3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy 3+ concentrations. These results indicate that 2.0 mol% Dy 3+ ions doped nano-garnet could be useful for white light emitting device applications

  13. Late-time particle emission from laser-produced graphite plasma

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, S. S.; Hassanein, A.; Polek, M. [School of Nuclear Engineering, Center for Materials Under Extreme Environment, Purdue University, West Lafayette, Indiana 47907 (United States)

    2011-09-01

    We report a late-time ''fireworks-like'' particle emission from laser-produced graphite plasma during its evolution. Plasmas were produced using graphite targets excited with 1064 nm Nd: yttrium aluminum garnet (YAG) laser in vacuum. The time evolution of graphite plasma was investigated using fast gated imaging and visible emission spectroscopy. The emission dynamics of plasma is rapidly changing with time and the delayed firework-like emission from the graphite target followed a black-body curve. Our studies indicated that such firework-like emission is strongly depended on target material properties and explained due to material spallation caused by overheating the trapped gases through thermal diffusion along the layer structures of graphite.

  14. Late-time particle emission from laser-produced graphite plasma

    International Nuclear Information System (INIS)

    Harilal, S. S.; Hassanein, A.; Polek, M.

    2011-01-01

    We report a late-time ''fireworks-like'' particle emission from laser-produced graphite plasma during its evolution. Plasmas were produced using graphite targets excited with 1064 nm Nd: yttrium aluminum garnet (YAG) laser in vacuum. The time evolution of graphite plasma was investigated using fast gated imaging and visible emission spectroscopy. The emission dynamics of plasma is rapidly changing with time and the delayed firework-like emission from the graphite target followed a black-body curve. Our studies indicated that such firework-like emission is strongly depended on target material properties and explained due to material spallation caused by overheating the trapped gases through thermal diffusion along the layer structures of graphite.

  15. Double-sided laser beam welded T-joints for aluminum-lithium alloy aircraft fuselage panels: Effects of filler elements on microstructure and mechanical properties

    Science.gov (United States)

    Han, Bing; Tao, Wang; Chen, Yanbin; Li, Hao

    2017-08-01

    In the current work, T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys for aircraft fuselage panels have been fabricated by double-sided fiber laser beam welding with different filler wires. A new type wire CW3 (Al-6.2Cu-5.4Si) was studied and compared with conventional wire AA4047 (Al-12Si) mainly on microstructure and mechanical properties. It was found that the main combined function of Al-6.2%Cu-5.4%Si in CW3 resulted in considerable improvements especially on intergranular strength, hot cracking susceptibility and hoop tensile properties. Typical non-dendritic equiaxed zone (EQZ) was observed along welds' fusion boundary. Hot cracks and fractures during the load were always located within the EQZ, however, this typical zone could be restrained by CW3, effectively. Furthermore, changing of the main intergranular precipitated phase within the EQZ from T phase by AA4047 to T2 phase by CW3 also resulted in developments on microscopic intergranular reinforcement and macroscopic hoop tensile properties. In addition, bridging caused by richer substructure dendrites within CW3 weld's columnar zone resulted in much lower hot cracking susceptibility of the whole weld than AA4047.

  16. Wideband and high-gain frequency stabilization of a 100-W injection-locked Nd:YAG laser for second-generation gravitational wave detectors.

    Science.gov (United States)

    Ohmae, Noriaki; Moriwaki, Shigenori; Mio, Norikatsu

    2010-07-01

    Second-generation gravitational wave detectors require a highly stable laser with an output power greater than 100 W to attain their target sensitivity. We have developed a frequency stabilization system for a 100-W injection-locked Nd:YAG (yttrium aluminum garnet) laser. By placing an external wideband electro-optic modulator used as a fast-frequency actuator in the optical path of the slave output, we can circumvent a phase delay in the frequency control loop originating from the pole of an injection-locked slave cavity. Thus, we have developed an electro-optic modulator made of a MgO-doped stoichiometric LiNbO(3) crystal. Using this modulator, we achieve a frequency control bandwidth of 800 kHz and a control gain of 180 dB at 1 kHz. These values satisfy the requirement for a laser frequency control loop in second-generation gravitational wave detectors.

  17. Atomistic simulations of ultra-short pulse laser ablation of aluminum: validity of the Lambert-Beer law

    Science.gov (United States)

    Eisfeld, Eugen; Roth, Johannes

    2018-05-01

    Based on hybrid molecular dynamics/two-temperature simulations, we study the validity of the application of Lambert-Beer's law, which is conveniently used in various modeling approaches of ultra-short pulse laser ablation of metals. The method is compared to a more rigorous treatment, which involves solving the Helmholtz wave equation for different pulse durations ranging from 100 fs to 5 ps and a wavelength of 800 nm. Our simulations show a growing agreement with increasing pulse durations, and we provide appropriate optical parameters for all investigated pulse durations.

  18. Evaluation of self-absorption coefficients of aluminum emission lines in laser-induced breakdown spectroscopy measurements

    International Nuclear Information System (INIS)

    El Sherbini, A.M.; El Sherbini, Th.M.; Hegazy, H.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In quantitative Laser Induced Breakdown Spectroscopy (LIBS) measurements it is essential to account for the effect of self-absorption on the emission lines intensity. In order to quantify this effect, in this paper we propose a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of self-absorption on line intensity. The method, based on a homogeneous plasma model, is applicable when the plasma electron density is known and in particular to lines whose Stark broadening parameter is available

  19. K-shell spectra from hot dense aluminum layers buried in carbon and heated by ultrashort laser pulses

    International Nuclear Information System (INIS)

    Eidmann, K.; Andiel, U.; Pisani, F.; Hakel, P.; Mancini, R.C.; Junkel-Vives, G.C.; Abdallah, J.; Witte, K.

    2003-01-01

    Ultrashort laser pulses allow for the generation of hot plasmas near solid state densities. For this purpose a Ti:Sapphire laser was used, which delivers after frequency doubling, pulses of high contrast with an energy of about 60 mJ and a duration of 150 fs at 395 nm. The typical intensity on the target was a few 10 17 W/cm 2 . To achieve a high degree of uniformity we used targets consisting of a 25 nm thin Al tracer layer buried at different depths up to 400 nm in solid carbon. Time-integrated Al K-shell spectra are presented. Characteristic features of the spectra are significant high-order satellite line emission, strong line broadening and a center-of-mass line shift to the red, which was observed in transitions from principal quantum number n=2 or 3 to 1. Accurate measurement of the shift was made possible by using the cold Si K α line as an absolute wavelength calibration. In addition to time-integrated measurements, we used an ultrafast X-ray streak camera to obtain time and spectrally resolved spectra. Typical durations of the Ly α and He α lines are in the range 2-4 ps. The experimental results are compared with a time-dependent model, which combines hydrodynamic simulations, time-dependent atomic kinetics, detailed spectral line shapes including line shifts, and radiation transport

  20. SEM evaluation of the morphological changes in hard dental tissues prepared by Er: YAG laser and rotary instruments

    Directory of Open Access Journals (Sweden)

    Tomov Georgi

    2010-09-01

    Full Text Available Effective ablation of dental hard tissues by means of the erbium:yttrium-aluminum garnet (Er: YAG laser has been reported recently, and its application to caries removal and cavity preparation has been expected. However, few studies have investigated the morphological changes in hard dental tissues after Er: YAG laser caries treatment. In the present study the morphological changes in hard dental tissues after Er: YAG laser caries ablation in vitro was compared with that of conventional mechanical treatment. Thirty extracted human teeth with caries were used. Ten tooth was treated with the Er: YAG laser, and the other was treated with a conventional steel and diamond burs. Laser treatment was performed by means of a non-contact irradiation modes with cooling water spray, with a new Er: YAG laser (LiteTouch. Conventional bur treatment was conducted by means of a low-speed micromotor and air turbine with water cooling. Scanning electron microscope (SEM observations were performed for each treatment. The Er: YAG laser ablated carious dentin effectively with minimal thermal damage to the surrounding intact dentin, and removed infected and softened carious dentin to the same degree as the burtreatment. In addition, a lower degree of vibration was noted with the Er: YAG laser treatment. The SEM examination revealed characteristic micro-irregularities of the lased dentin and enamel surfaces with potential benefits for adhesive restorations. Our results show that the Er: YAG laser is promising as a new technical modality for caries treatment

  1. On the physics of laser-induced selective photothermolysis of hair follicles: Influence of wavelength, pulse duration, and epidermal cooling.

    Science.gov (United States)

    Svaasand, Lars O; Nelson, J Stuart

    2004-01-01

    The physical basis for optimization of wavelength, pulse duration, and cooling for laser-induced selective photothermolysis of hair follicles in human skin is discussed. The results indicate that the most important optimization parameter is the cooling efficiency of the technique utilized for epidermal protection. The optical penetration is approximately the same for lasers at 694, 755, and 800 nm. The penetration of radiation from Nd:yttrium-aluminum-garnet lasers at 1064 nm is, however, somewhat larger. Photothermal damage to the follicle is shown to be almost independent of laser pulse duration up to 100 ms. The results reveal that epidermal cooling by a 30-80-ms-long cryogen spurt immediately before laser exposure is the only efficient technique for laser pulse durations less than 10 ms. For longer pulse durations in the 30-100 ms range, protection can be done efficiently by skin cooling during laser exposure. For laser pulses of 100 ms, an extended precooling period, e.g., by bringing a cold object into good thermal contact with the skin for about 1 s, can be of value. Thermal quenching of laser induced epidermal temperature rise after pulsed exposure can most efficiently be done with a 20 ms cryogen spurt applied immediately after irradiation. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

  2. Nonlinear FMR spectra in yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

    2015-12-01

    Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

  3. Nd:YAG laser for epithelial ingrowth after laser in situ keratomileusis.

    Science.gov (United States)

    Mohammed, Osama Ali; Mounir, Amr; Hassan, Amin Aboali; Alsmman, Alahmady Hamad; Mostafa, Engy Mohamed

    2018-05-04

    To evaluate the efficacy of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK). Fifty-eight patients with epithelial ingrowth presented to Sohag refractive center, Sohag, Egypt, between January 2015 and March 2017. Only 41 patients (18 females and 23 males, mean age: 33.4 years) involving 41 eyes were indicated for treatment by Nd:YAG laser as the rest of the eyes were only under observation. Patients with epithelial ingrowth were recognized at a mean of 6 months after primary LASIK procedure (range: 2-16 months). Four eyes had undergone previous LASIK enhancements. Four eyes had the epithelial ingrowth removed by flap lift and scrapping. The mean intensity of the spots used was 0.8 mJ with variable number of shots depending on the size and density of the epithelial ingrowth area. Twenty-eight eyes showed complete regression after one session, while the rest necessitated 2-3 sessions for complete resolution. Mean follow-up period was 8 months (range 5-12 months). Epithelial ingrowth was treated successfully in all 41 eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6 months with no complications reported. YAG laser is a simple, effective outpatient procedure for the management of epithelial ingrowth after LASIK.

  4. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates are simi...

  5. Fabrication and characterization of Bismuth-Cerium composite iron garnet epitaxial films for magneto optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Chandra Sekhar, M.; Singh, Mahi R. [Department of Physics and Astronomy, 1151, Richmond Street, Western University, London, Ontario N6A 3K7 (Canada)

    2012-10-15

    The Bi{sub x}Ce{sub 3-x}Fe{sub 5}O{sub 12} (x = 0.8) epitaxial films of high quality were grown by means of pulsed laser deposition on paramagnetic substrates of Gadolinium Gallium Garnet. We study the modifications of substitutions in the parent garnet Y{sub 3}Fe{sub 5}O{sub 12} that produces a higher magneto-optical response at communication wavelengths. These films displayed a strong in plane textures which are treated in argon as well as reduced atmosphere conditions. The elemental constituents of these films were confirmed by energy dispersive-X ray analysis, elastic recoil detection system, Rutherford backscattering spectroscopy, and X-ray photoelectron spectroscopy measurements. The transmittance spectra were measured and found these films exhibit good transmittance values. The transmittance-spectra were fitted with the theoretical model and the optical constants such as refractive index and absorption edge were evaluated. The highest (negative) Faraday rotation was found for these films treated in the environment of Ar + H{sub 2}. A density matrix theory has been developed for the Faraday rotation and a good agreement between the theory and experiment is found. These epitaxial garnet films can be used in a wide range of frequencies from visible to infrared spectra making them ideal for many magneto optical applications. Therefore, these films may overcome many issues in fabricating all optical isolators which is the viable solution for integrated photonics.

  6. Treatment of extensive urethral hemangioma with KTP/532 laser.

    Science.gov (United States)

    Lauvetz, R W; Malek, R S; Husmann, D A

    1996-01-01

    Urethral hemangiomas are rare. They vary in size from pinpoint masses to extensive honeycomb-shape deformities leading to significant hematuria. For extensive lesions, therapeutic options have included extensive surgical resection and reconstruction or multistaged neodymium:yttrium-aluminum-garnet (Nd:YAG) laser photocoagulation. We report our experience with the use of potassium titanyl phosphate (KTP/532) laser for treatment of the extensive form. A 7-year-old boy presented with a 2-week history of urethral bleeding. He had extensive hemangiomas of the genital and perineal regions. Cystourethroscopy disclosed diffusely scattered honeycomb-shape hemangiomatous malformation of the anterior urethra. KTP/532 laser energy was delivered transurethrally to the hemangiomatous areas until they blanched. The Foley catheter was removed 24 hours postoperatively, and the patient voided clear urine without difficulty. He has remained trouble-free for more than 2 years. Judicious endoscopic single-stage therapy with KTP/532 laser may obviate open surgical intervention in most cases of extensive and symptomatic urethral hemangiomas. In view of our observation and the literature, KTP/532 laser therapy should be considered the first line of treatment.

  7. Efficient and stable laser-driven white lighting

    Directory of Open Access Journals (Sweden)

    Kristin A. Denault

    2013-07-01

    Full Text Available Laser-based white lighting offers a viable option as an efficient and color-stable high-power solid-state white light source. We show that white light generation is possible using blue or near-UV laser diodes in combination with yellow-emitting cerium-substituted yttrium aluminum garnet (YAG:Ce or a mixture of red-, green-, and blue-emitting phosphors. A variety of correlated color temperatures (CCT are achieved, ranging from cool white light with a CCT of 4400 K using a blue laser diode to a warm white light with a CCT of 2700 K using a near-UV laser diode, with respective color rendering indices of 57 and 95. The luminous flux of these devices are measured to be 252 lm and 53 lm with luminous efficacies of 76 lm/W and 19 lm/W, respectively. An estimation of the maximum efficacy of a device comprising a blue laser diode in combination with YAG:Ce is calculated and the results are used to optimize the device.

  8. Isotopic chronometry of zoned garnets: Growth kinetics and metamorphic histories

    International Nuclear Information System (INIS)

    Vance, D.; O'Nions, R.K.

    1990-01-01

    Basic information on the chronological and pressure-temperature evolution of regional metamorphic terrains may in principle be derived from metamorphic garnets because of the similarly low diffusivities of Sm, Nd and major cations in this mineral. We report here Sm-Nd and Rb-Sr isotopic and major element data on prograde garnets from regionally metamorphosed pelites from Newfoundland. The garnets preserve a prograde major element zonation as well as a sympathetic variation in Sm/Nd ratio. Sm-Nd data for separated portions of the garnet from core to rim provide both upper limits on the time for garnet growth and demonstrate synchronous growth of different garnet grains on a hand specimen scale. The Rb-Sr data on the same garnet fractions are in general agreement with these results but in some cases cannot be interpreted in terms of growth. A minimum heating rate of 3 K Ma -1 is derived by combining the estimates for garnet growth time with the apparent temperature interval over which the garnet grew, deduced from the major element zonation. This value is similar to the minimum suggested by theoretical models for the thermal evolution of thickened continental crust. The growth rate is within the range of 1.3-19 mm Ma -1 , set respectively by the isotopic data and the likely upper limit for heating rate during regional metamorphism. These growth rates appear too slow to be controlled by surface reaction and suggest that other factors, such as transport, may be rate-limiting. In this case, the limits set of the effective diffusion coefficient for material transport to the growth site (=0.4-6.1x10 -17 m 2 s -1 ) suggest that grain boundary diffusion is probably the transport mechanism for supply of material to the growing garnet. (orig.)

  9. Unit for the nanosecond, laser, pulse photolysis in the ultraviolet region for a combination of photochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Pikel' ni, V F; Kolosov, V A; Kiryukhin, Yu I; Kondrat' ev, V A; Borovkova, V A; Tarasov, E N

    1976-06-01

    A description is given of a nanosecond laser unit for pulse photolysis in the ultraviolet region, by means of which it is possible to investigate the kinetics of the death of interstitial particles, their optical absorption and luminescence spectra, and also the photoconductivity induced by the laser radiation, at a time resolution of about 15 ns. As a source of powerful, stable uv-radiation, use is made of the fourth harmonic (266 nm) of radiation from an aluminum-yttrium garnet containing neodymium. The radiation power of the fourth harmonic attained 2 MW. The time of bringing the unit into the operating mode is considerably shortened because of the possibility of operating in a frequency mode. Absorption spectra of carbazole in hexane were obtained at 20/sup 0/C. (SJR)

  10. Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite.

    Science.gov (United States)

    Rosenheim, Brad E; Thorrold, Simon R; Roberts, Mark L

    2008-11-01

    The determination of (14)C in aragonite (CaCO(3)) decomposed thermally to CO(2) using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of (14)C from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO(2) despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO(2) gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO(2) generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO(2).

  11. Advances in Single-Crystal Fibers and Thin Rods Grown by Laser Heated Pedestal Growth

    Directory of Open Access Journals (Sweden)

    Gisele Maxwell

    2017-01-01

    Full Text Available Single-crystal fibers are an intermediate between laser crystals and doped glass fibers. They have the advantages of both guiding laser light and matching the efficiencies found in bulk crystals, which is making them ideal candidates for high-power laser and fiber laser applications. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc. and a polycrystalline clad of yttrium aluminum garnet (YAG that will exhibit good wave guiding properties. Direct growth or a combination of growth and cladding experiments are described. Scattering loss measurements at visible wavelengths, along with dopant profile characterization with damage threshold results, are also presented. For single-pass amplification, a single-pass linear gain of 7.4 was obtained for 29 nJ pulses of 5 ns duration at 1 MHz repetition rate. We also obtained a laser efficiency of over 58% in a diode-pumped configuration. These results confirm the potential for single-crystal fibers to overcome the limitations of the glass fibers commonly used in fiber lasers, making them prime candidates for high-power compact fiber lasers and amplifiers.

  12. Role of melt behavior in modifying oxidation distribution using an interface incorporated model in selective laser melting of aluminum-based material

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Dongdong, E-mail: dongdonggu@nuaa.edu.cn; Dai, Donghua [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016 (China); Institute of Additive Manufacturing (3D Printing), Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016 (China)

    2016-08-28

    A transient three dimensional model for describing the molten pool dynamics and the response of oxidation film evolution in the selective laser melting of aluminum-based material is proposed. The physical difference in both sides of the scan track, powder-solid transformation and temperature dependent physical properties are taken into account. It shows that the heat energy tends to accumulate in the powder material rather than in the as-fabricated part, leading to the formation of the asymmetrical patterns of the temperature contour and the attendant larger dimensions of the molten pool in the powder phase. As a higher volumetric energy density is applied (≥1300 J/mm{sup 3}), a severe evaporation is produced with the upward direction of velocity vector in the irradiated powder region while a restricted operating temperature is obtained in the as-fabricated part. The velocity vector continuously changes from upward direction to the downward one as the scan speed increases from 100 mm/s to 300 mm/s, promoting the generation of the debris of the oxidation films and the resultant homogeneous distribution state in the matrix. For the applied hatch spacing of 50 μm, a restricted remelting phenomenon of the as-fabricated part is produced with the upward direction of the convection flow, significantly reducing the turbulence of the thermal-capillary convection on the breaking of the oxidation films, and therefore, the connected oxidation films through the neighboring layers are typically formed. The morphology and distribution of the oxidation are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  13. Study of local-zone microstructure, strength and fracture toughness of hybrid laser-metal-inert-gas-welded A7N01 aluminum alloy joint

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaomin, E-mail: xmwang991011@163.com [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Li, Bo [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Li, Mingxing; Huang, Cui [School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China); Chen, Hui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan (China)

    2017-03-14

    Mechanical properties of hybrid laser-metal-inert-gas-welded A7N01-T5 aluminum alloy joints were studied by using local samples that were extracted from the base metal (BM), heat-affected zone (HAZ), and fusion zone (FZ) of the joint to investigate the triangular relationship of microstructure, strength and fracture toughness of the local zones. The BM had the highest yield strength, ultimate tensile strength (UTS) and lowest elongation, which contrasts with the FZ. The yield strength of the HAZ is lower than that of the BM, whereas its UTS is very close to that of the BM, and its elongation is higher than that of the BM. The fracture toughness of the three local zones decreased as HAZ>BM>FZ. To analyze differences in local mechanical behavior, the detailed microstructure of the three local zones was studied by optical microscopy and electron backscattered diffraction, whereas the fracture surface and precipitation were studied by scanning and transmission electron microscopy. The variation of grain size, especially the morphology and distribution of strengthening phase in HAZ in welding process is the key factor that leads to its different mechanical properties from that of BM, which can be elucidated by different dislocation mechanism, sheared mechanism or Orowan mechanism. The as-cast microstructure and second-phase particles that segregate between dendritic branches provide the FZ with the lowest yield strength and UTS. The factors including area fraction of the precipitates, the difference of strength between the matrix and the grain boundaries, the precipitate-free zone along grain boundaries, as well as the grain boundaries angle are taken into account to explain the difference of fracture toughness among BM, HAZ and FZ, and their fracture modes.

  14. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    International Nuclear Information System (INIS)

    Genin, F.Y.; Michlitsch, K.; Furr, J.; Kozlowski, M.R.; Krulevitch, P.

    1997-01-01

    1-μm thick circular dots, 10-250 μm dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions

  15. Yttrium aluminium garnet under pressure: Structural, elastic, and vibrational properties from ab initio studies

    International Nuclear Information System (INIS)

    Monteseguro, V.; Rodríguez-Hernández, P.; Muñoz, A.

    2015-01-01

    The structural, elastic, and vibrational properties of yttrium aluminum garnet Y 3 Al 5 O 12 are studied under high pressure by ab initio calculations in the framework of the density functional theory. The calculated ground state properties are in good agreement with the available experimental data. Pressure dependences of bond length and bulk moduli of the constituent polyhedra are reported. The evolution of the elastic constants and the major elastic properties, Young and shear modulus, Poisson's ratios, and Zener anisotropy ratio, are described. The mechanical stability is analyzed, on the light of “Born generalized stability criteria,” showing that the garnet is mechanically unstable above 116 GPa. Symmetries, frequencies, and pressure coefficients of the Raman-active modes are discussed on the basis of the calculated total and partial phonon density of states, which reflect the dynamical contribution of each atom. The relations between the phonon modes of Y 3 Al 5 O 12 and the internal and external molecular modes of the different polyhedra are discussed. Infrared-active modes, as well as the silent modes, and their pressure dependence are also investigated. No dynamical instabilities were found below 116 GPa

  16. Transmission of Er:YAG laser through different dental ceramics.

    Science.gov (United States)

    Sari, Tugrul; Tuncel, Ilkin; Usumez, Aslihan; Gutknecht, Norbert

    2014-01-01

    The aim of this study was to determine the erbium-doped yttrium aluminum garnet (Er:YAG) laser transmission ratio through different dental ceramics with different thicknesses. Laser debonding procedure of adhesively luted all-ceramic restorations is based on the transmission of laser energy through the ceramic and the ablation of resin cement, because of the transmitted laser energy. Five different dental ceramics were evaluated in this study: sintered zirconium-oxide core ceramic, monolithic zirconium-oxide ceramic, feldspathic ceramic, leucite-reinforced glass ceramic, and lithium disilicate-reinforced glass ceramic. Two ceramic discs with different thicknesses (0.5 and 1 mm) were fabricated for each group. Ceramic discs were placed between the sensor membrane of the laser power meter and the tip of the contact handpiece of an Er:YAG laser device with the aid of a custom- made acrylic holder. The transmission ratio of Er:YAG laser energy (500 mJ, 2 Hz, 1 W, 1000 μs) through different ceramic discs was measured with the power meter. Ten measurements were made for each group and the results were analyzed with two way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests. The highest transmission ratio was determined for lithium disilicate-reinforced ceramic with 0.5 mm thickness (88%) and the lowest was determined for feldspathic ceramic with 1 mm thickness (44%). The differences among the different ceramics and between the different thicknesses were significant (pCeramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all-ceramic restorations.

  17. Can thermal lasers promote skin wound healing?

    Science.gov (United States)

    Capon, Alexandre; Mordon, Serge

    2003-01-01

    Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced

  18. Role of marble microstructure in near-infrared laser-induced damage during laser cleaning

    International Nuclear Information System (INIS)

    Rodriguez-Navarro, Carlos; Rodriguez-Navarro, Alejandro; Elert, Kerstin; Sebastian, Eduardo

    2004-01-01

    When marble is cleaned by nanosecond neodymium yttrium-aluminum-garnet lasers (1064 nm), strongly absorbing surface contaminants are removed at fluences substantially below the damage threshold for the much less absorptive marble substrate. Recent studies have shown, however, that unacceptable roughening of the marble surface also may occur at low fluences due to removal of individual grains. In order to elucidate this effect, we have compared the low-fluence response of marbles with two different grain sizes and single-crystal calcite, in the fluence range 0.12-1.25 J cm-2. Damage was greater in fine-grained than coarse-grained marble, and did not occur in the single-crystal calcite at these fluences. The temperature rise following defect-mediated absorption triggers thermal plasma emission and generates shock waves; the concomitant surface damage depends on the size and crystallographic orientation of the crystals. Laser irradiation anneals the defects and increases ''crystallite size.'' The implications for the laser-assisted cleaning of marble artworks are outlined

  19. Garnet film rotator applied in polarizing microscope for domain image modulation (abstract)

    Science.gov (United States)

    Wakabayashi, K.; Numata, T.; Inokuchi, S.

    1991-04-01

    A garnet film polarization rotator placed before the analyzer in a polarizing microscope was investigated to obtain the difference image of a positive and a negative one of magnetic domain in real time along with an image processor. In the difference image, a nonmagnetic image can be reduced and hence the weak magnetic contrast enhanced. Theoretical calculation of S/N and contrast C of the domain image as a function of the rotation shows they take maxima at the rotation angle of 2.6° and 0.1°, respectively, with the extinction ratio of e=4×10-6 of a polarizing microscope. Thus, since the thickness of the garnet film required is 1 μm or so, the absorption by the garnet rotator does not bring a serious problem even in a visible region for the domain observation. The optimum rotation of the rotator for a high quality observation was obtained by a quantitative study of images obtained experimentally as well as by a visual evaluation. A magnetically unsaturated garnet film with perpendicular magnetization (i.e., multidomain) was employed as a rotator, in which the polarization rotation angle θm of the undeflected beam with respect to the light diffraction could be continuously varied by an applied magnetic field. The dependences of S/N and C on θm were measured, resulting in a well agreement between the measured and the calculated. The visually best image was obtained at θm=0.5° which made the product of S/N and C maximum. The domain image of the Kerr rotation angle of θk=0.22° was observed in S/N=47 dB and C=0.4 when Ar+ laser (λ=515 nm) of tenths of a watt was employed as a light source. Since the domain image with 47 dB S/N does not need an image summation for a noise reduction, a garnet film rotator makes it possible to invert the contrast of a domain image in a real time for an improved domain observation.

  20. Osteogenic potential of laser modified and conditioned titanium zirconium surfaces

    Directory of Open Access Journals (Sweden)

    P David Charles

    2016-01-01

    Full Text Available Statement of Problem: The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established. Purpose: The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG laser surface treatment of TiZr implant alloy on their osteogenic potential. Materials and Methods: Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy. Results: Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential. Conclusion: Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.

  1. Application of YAG laser cladding to the flange seating surface

    International Nuclear Information System (INIS)

    Nakanishi, Koki; Ninomiya, Kazuyuki; Nezaki, Koji

    1999-01-01

    Stainless cladding on carbon steel is usually conducted by shielded metal arc welding (SMAW) or gas tungsten arc welding (GTAW). YAG ( Yttrium-Aluminum-Garnet) laser welding is superior to these methods of welding in the following respects : (1) The heat affected zone (HAZ) is narrower and there is less distortion. (2) YAG laser cladding has the required chemical compositions, even with possibly fewer welding layers under controlled dilution. (3) Greater welding speed. YAG laser cladding application to vessel flange seating surfaces was examined in this study and the results are discussed. The following objectives were carried out : (1) Determination of welding conditions for satisfactory cladding layers and (2) whether cladding would be adequately possible at a cornered section of a stair-like plate, assuming actual flange shape. (3) Measurement of welding distortion and heat affected zone in carbon steel. The welding conditions for producing no-crack deposit with low dilution in carbon steel were clarified and welding by which cladding at cornered section would be possible was achieved. welding distortion by YAG laser was found less than with GTAW and HAZ made by first layer welding could be tempered appropriately by second layer welding. (author)

  2. Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study

    Science.gov (United States)

    Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

    2017-11-01

    Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18 J/cm2 in the mesentery model and from 36 to 31 J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions.

  3. Dating Ore Deposit Using Garnet U–Pb Geochronology: Example from the Xinqiao Cu–S–Fe–Au Deposit, Eastern China

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2018-01-01

    Full Text Available The large Xinqiao Cu–S–Fe–Au deposit in the Tongling ore district, Eastern China, is characterized by a large-scale stratiform orebody, in which garnet is widely distributed as the main gangue mineral associated with mineralization. Xinqiao garnet can be divided into early (Grt1 and late (Grt2 generations based on extensive back-scattered electron (BSE imaging observations. Laser ablation (LA-ICP-MS trace element and U–Pb isotope composition analyses indicate that uranium occurs homogeneously within the Xinqiao garnet, and Grt1 and Grt2 have weighted average 207Pb-corrected 206Pb/238U ages of 137.0 ± 7.8 Ma (Mean standard weighted deviation (MSWD = 4.9 and 129.6 ± 7.1 Ma (MSWD = 1.6, respectively, similar to the zircon U–Pb age (139.6 ± 1.5 Ma of the Jitou intrusion. These garnet U–Pb ages, combined with the low MnO content and various Y/Ho ratios, suggest that the Xinqiao garnet is likely to have a magmatic hydrothermal replacement origin associated with the Jitou stock. Based on previous studies of the Xinqiao deposit, we infer that the Xinqiao stratiform orebody may have formed from the Early Cretaceous magmatic hydrothermal fluids associated with the Jitou stock, and may have been generated by the Early Cretaceous tectono-thermal event in Eastern China.

  4. High-coercive garnet films for thermo-magnetic recording

    International Nuclear Information System (INIS)

    Berzhansky, V N; Danishevskaya, Y V; Nedviga, A S; Milyukova, H T

    2016-01-01

    The possibility of using high-coercive of garnet films for thermo-magnetic recording is related with the presence of the metastable domain structure, which arises due to a significant mismatch of the lattice parameters of the film and the substrate. In the work the connection between facet crystal structure of elastically strained ferrite garnets films and the domain structure in them is established by methods of phase contrast and polarization microscopy. (paper)

  5. Garnets from the Camafuca-Camazambo kimberlite (Angola

    Directory of Open Access Journals (Sweden)

    Correia Eugénio A.

    2006-01-01

    Full Text Available This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004 and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10 and Ca-saturated (G9 garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa. The occurrence of diamond stability field garnets (G10D is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

  6. High-resolution structural characterization and magnetic properties of epitaxial Ce-doped yttrium iron garnet thin films

    Science.gov (United States)

    Li, Zhong; Vikram Singh, Amit; Rastogi, Ankur; Gazquez, Jaume; Borisevich, Albina Y.; Mishra, Rohan; Gupta, Arunava

    2017-07-01

    Thin films of magnetic garnet materials, e.g. yttrium iron garnet (Y3Fe5O12, YIG), are useful for a variety of applications including microwave integrated circuits and spintronics. Substitution of rare earth ions, such as cerium, is known to enhance the magneto-optic Kerr effect (MOKE) as compared to pure YIG. Thin films of Ce0.75Y2.25Fe5O12 (Ce:YIG) have been grown using the pulsed laser deposition (PLD) technique and their crystal structure examined using high resolution scanning transmission electron microscopy. Homogeneous substitution of Ce in YIG, without oxidation to form a separate CeO2 phase, can be realized in a narrow process window with resulting enhancement of the MOKE signal. The thermally generated signal due to spin Seebeck effect for the optimally doped Ce:YIG films has also been investigated.

  7. Neutron scattering study of yttrium iron garnet

    Science.gov (United States)

    Shamoto, Shin-ichi; Ito, Takashi U.; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato; Akatsu, Mitsuhiro; Kodama, Katsuaki; Nakao, Akiko; Moyoshi, Taketo; Munakata, Koji; Ohhara, Takashi; Nakamura, Mitsutaka; Ohira-Kawamura, Seiko; Nemoto, Yuichi; Shibata, Kaoru

    2018-02-01

    The nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y3Fe5O12 have been studied using neutron scattering. The refined nuclear structure is distorted to a trigonal space group of R 3 ¯ . The highest-energy dispersion extends up to 86 meV. The observed dispersions are reproduced by a simple model with three nearest-neighbor-exchange integrals between 16 a (octahedral) and 24 d (tetrahedral) sites, Ja a, Ja d, and Jd d, which are estimated to be 0.00 ±0.05 , -2.90 ±0.07 , and -0.35 ±0.08 meV, respectively. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of q -integrated dynamical spin susceptibility χ″(E ) exhibits a square-root energy dependence at low energies. The magnon density of state is estimated from χ″(E ) obtained on an absolute scale. The value is consistent with the single chirality mode for the magnon branch expected theoretically.

  8. Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

    Science.gov (United States)

    Sato, Y.; Ogasawara, Y.

    2015-12-01

    Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz

  9. Do We Really Need to Wear Proper Eye Protection When Using Holmium:YAG Laser During Endourologic Procedures? Results from an Ex Vivo Animal Model on Pig Eyes.

    Science.gov (United States)

    Villa, Luca; Cloutier, Jonathan; Compérat, Eva; Kronemberg, Peter; Charlotte, Frederic; Berthe, Laurent; Rouchausse, Yann; Salonia, Andrea; Montorsi, Francesco; Traxer, Olivier

    2016-03-01

    We sought to evaluate the effect of holmium:yttrium-aluminum-garnet (Ho:YAG) laser exposure on ex vivo pig eyes and to test the protective action of different glasses in preventing eye lesions in case of accident. We pointed the tip of a Ho:YAG laser fiber from different distances (0, 3, 5, 8, 10, and 20 cm, respectively) toward the center of the pupil of the pig eye. The Ho:YAG laser was activated for 1 or 5 seconds at three different settings (0.5 J-20 Hz, 1 J-10 Hz, and 2 J-10 Hz, respectively). The experiment was repeated using laser safety glasses and eyeglasses. A total of 78 pig eyes were used. The effects of the Ho:YAG laser on pig eyes were assessed by histopathology. Comparable laser emission experiments were performed on thermal paper at different distances using different pulse energies. Ho:YAG laser-induced corneal lesions were observed in unprotected eyes, ranging from superficial burning lesions to full-thickness necrotic areas, and were directly related to pulse energy and time of exposure and inversely related to the distance from the eye. When the laser was placed 5 cm or more, no corneal damage was observed regardless of the laser setting and the time of exposure. Similar distance/energy level relationships were observed on thermal paper. No damage was observed to the lens or the retina in any of the Ho-YAG laser-treated eyes or in any of the eyes protected by laser safety and eyeglasses. Ho:YAG lasers can cause damage when set to high energy, but only to the cornea, from close distances (0-5 cm) and in the absence of eye protection. Eyeglasses are equally effective in preventing laser damage as laser safety glasses.

  10. Magneto-optical study of holmium iron garnet Ho3Fe5O12

    Science.gov (United States)

    Kalashnikova, A. M.; Pavlov, V. V.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Pisarev, R. V.

    2012-09-01

    Bulk holmium iron garnet Ho3Fe5O12 is a cubic ferrimagnet with Curie temperature TC = 567 K and magnetization compensation point in the range 130-140 K. The magneto-optical data are presented for a holmium iron garnet Ho3Fe5O12 film, ˜10 μm thick, epitaxially grown on a (111)-type gadolinium-gallium garnet Gd3Ga5O12 substrate. A specific feature of this structure is that the parameters of the bulk material, from which the film was grown, closely match the substrate ones. The temperature and field dependences of Faraday rotation as well as the temperature dependence of the domain structure in zero field were investigated. The compensation point of the structure was found to be Tcomp = 127 K. It was shown that the temperature dependence of the characteristic size of domain structure diverges at this point. Based on the obtained results we established that the magnetic anisotropy of the material is determined by both uniaxial and cubic contributions, each characterized by different temperature dependence. A complex shape of hysteresis loops and sharp changes of the domain pattern with temperature indicate the presence of collinear-noncollinear phase transitions. Study of the optical second harmonic generation was carried out using 100 fs laser pulses with central photon energy E = 1.55 eV. The electric dipole contribution (both crystallographic and magnetic) to the second harmonic generation was observed with high reliability despite a small mismatch of the film and substrate parameters.

  11. Application of laser cladding method to small-diameter stainless steel pipes in actual nuclear plant

    International Nuclear Information System (INIS)

    Atago, Y.; Yamadera, M.; Tsuji, H.; Shiraiwa, T.; Kanno, M.

    1995-01-01

    Recently, to prevent stress corrosion cracking (SCC) the material of stainless steel (Type 304), a laser cladding method which produces a highly corrosion-resisting coating (cladding) to be formed on the surface of the material was developed. This is applicable to a long distance and narrow space, because of the good accessibility of the YAG (Yttrium-Aluminum Garnet) laser beam that can be transmitted through an optical fiber. In this method, a paste mixed metallic powder and heating resistive organic solvent is firstly placed on the inner surface of a small pipe and then a YAG laser beam transmitted through an optical fiber is irradiated to the paste, which will be melted and formed a clad subsequently, which is excellent in corrosion resistance. Finally, it can be achieved further resistance against the SCC due to the clad layer formed thus on the surface of the material. Recently, this Laser Cladding method was practically and successfully applied to the actual BWR Nuclear Power Plant in Japan. This report introduces the laser cladding technique, the equipments developed for practical application in the field

  12. Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

    Energy Technology Data Exchange (ETDEWEB)

    Benafan, O., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu; Vaidyanathan, R., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu [Advanced Materials Processing and Analysis Center (AMPAC), Materials Science and Engineering, Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Chen, S.-Y.; Kar, A. [Laser-Advanced Materials Processing Laboratory, Center for Research and Education in Optics and Lasers (CREOL), College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States)

    2015-12-15

    Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell’s equations and heat conduction.

  13. Studies on fatigue life enhancement of pre-fatigued spring steel specimens using laser shock peening

    International Nuclear Information System (INIS)

    Ganesh, P.; Sundar, R.; Kumar, H.; Kaul, R.; Ranganathan, K.; Hedaoo, P.; Raghavendra, G.; Anand Kumar, S.; Tiwari, P.; Nagpure, D.C.; Bindra, K.S.; Kukreja, L.M.; Oak, S.M.

    2014-01-01

    Highlights: • Laser peening significantly extended fatigue life of pre-fatigued spring steel. • Increase in fatigue life of laser peened specimens was more than 15 times. • Black PVC tape is an effective coating for laser peening of ground surfaces. • Repeat peening repaired local surface melted regions on laser peened surface. • Technique is effective for life extension of in-service automobile parts. - Abstract: SAE 9260 spring steel specimens after enduring 50% of their mean fatigue life were subjected to laser shock peening using an in-house developed 2.5 J/7 ns pulsed Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser for studying their fatigue life enhancement. In the investigated range of process parameters, laser shock peening resulted in the extension of fatigue life of these partly fatigue damaged specimens by more than 15 times. Contributing factors for the enhanced fatigue life of laser peened specimens are: about 400 μm thick compressed surface layer with magnitude of surface stress in the range of −600 to −700 MPa, about 20% increase in surface hardness and unaltered surface finish. For laser peening of ground steel surface, an adhesive-backed black polyvinyl chloride (PVC) tape has been found to be a superior sacrificial coating than conventionally used black paint. The effect of repeated laser peening treatment was studied to repair locally surface melted regions and the treatment has been found to be effective in re-establishing desired compressive stress pattern on the erstwhile tensile-stressed surface

  14. Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

    Science.gov (United States)

    Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

    2015-12-01

    The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

  15. Platinum/yttrium iron garnet inverted structures for spin current transport

    Energy Technology Data Exchange (ETDEWEB)

    Aldosary, Mohammed; Li, Junxue; Tang, Chi; Xu, Yadong; Shi, Jing [Department of Physics and Astronomy and SHINES Energy Frontier Research Center, University of California, Riverside, California 92521 (United States); Zheng, Jian-Guo [Irvine Materials Research Institute, University of California, Irvine, California 92697 (United States); Bozhilov, Krassimir N. [Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside, California 92521 (United States)

    2016-06-13

    30-80 nm thick yttrium iron garnet (YIG) films are grown by pulsed laser deposition on a 5 nm thick sputtered Pt atop gadolinium gallium garnet substrate (GGG) (110). Upon post-growth rapid thermal annealing, single crystal YIG(110) emerges as if it were epitaxially grown on GGG(110) despite the presence of the intermediate Pt film. The YIG surface shows atomic steps with the root-mean-square roughness of 0.12 nm on flat terraces. Both Pt/YIG and GGG/Pt interfaces are atomically sharp. The resulting YIG(110) films show clear in-plane uniaxial magnetic anisotropy with a well-defined easy axis along 〈001〉 and a peak-to-peak ferromagnetic resonance linewidth of 7.5 Oe at 9.32 GHz, similar to YIG epitaxially grown on GGG. Both spin Hall magnetoresistance and longitudinal spin Seebeck effects in the inverted bilayers indicate excellent Pt/YIG interface quality.

  16. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser.

    Science.gov (United States)

    Goldman, Alberto; Wollina, Uwe

    2014-01-01

    Permanent makeup is a cosmetic tattoo that is used to enhance one's appearance, and which has become more popular among middle-aged and elderly women. A couple of benefits seem to be associated with permanent tattoos in the elderly: saving time (wake up with makeup); poor eyesight (difficult to apply makeup); and saving money. On the other hand, cosmetic tattoos bear the same risks as other tattoo procedures. We report on fading and unintended hyperpigmentation after tattooing on eyebrows and eyelids, and discuss the scientific and anatomical background behind the possible cause. Dermatochalasis may be a possible risk factor for excessive unwanted discolorations. Q-switched neodymium-doped yttrium aluminum garnet laser is an appropriate and safe therapeutic tool that can manage such adverse effects. Consumer protection warrants better information and education of the risks of cosmetic tattoos - in particular, for elderly women.

  17. Analysis of garnets from the archaeological sites in Slovenia

    Energy Technology Data Exchange (ETDEWEB)

    Šmit, Ž., E-mail: ziga.smit@fmf.uni-lj.si [Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana (Slovenia); Jožef Stefan Institute, Ljubljana (Slovenia); Fajfar, H. [Jožef Stefan Institute, Ljubljana (Slovenia); Jeršek, M. [Slovenian Museum of National History, Ljubljana (Slovenia); Knific, T. [National Museum of Slovenia, Ljubljana (Slovenia); Lux, J. [Institute for the Protection of Cultural Heritage of Slovenia, Ljubljana (Slovenia)

    2014-06-01

    Garnets (62 individual stones) originating from the Migration Period cemeteries and hilltop settlements in Slovenia were analyzed by the combined PIXE/PIGE method for their chemical composition. Typologically, the analyzed stones may be classified as almandines originating from the sites in India, belonging to types I and II according to Calligaro. A smaller group of pyraldines intermediate between almandines and pyropes was also determined; identified as type III, their source is most likely in Sri Lanka. No garnets from Bohemia (Czech Republic) have been discovered, which may be related to important political changes in the 7th c. AD, induced by Slavic and Avaric migrations.

  18. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  19. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T(e and N(e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T(e and N(e for the aluminum in aluminum alloys using an optical fiber probe.

  20. Study etching characteristics of a track detector CR-39 with ultraviolet laser irradiation

    International Nuclear Information System (INIS)

    Dwaikat, Nidal; Iida, Toshiyuki; Sato, Fuminobu; Kato, Yushi; Ishikawa, Ippei; Kada, Wataru; Kishi, Atsuya; Sakai, Makoto; Ihara, Yohei

    2007-01-01

    The effect of pulsed ultraviolet Indium-doped Yttrium Aluminum Garnet (UV-In:YAG) laser of λ=266 nm, pulse energy 42 mJ/pulse at repetition rate10 Hz on the etching characteristics of Japanese CR-39 was studied at various energy intensities. Fifteen detectors were divided into two sets, each of seven samples and one sample was kept as a reference.The first set (post-exposed) was first exposed to alpha radiation with close contact to 241 Am and then treated in air with laser in the energy intensity range from 40 to160 J/cm 2 , 20 J/cm 2 in step. The second set (pre-exposed) was irradiated in reverse process (laser+alpha) with the same sources as the first set and under the same condition. The laser energy intensities ranged between 20 and 140 J/cm 2 , 20 J/cm 2 in step. For post-exposed samples (alpha+laser) bulk etch rate decreases up to 60 J/cm 2 and increases thereafter, while for pre-exposed samples (laser+alpha) the bulk etch rate oscillates without showing any precise periodicity. The bulk etch rate for both sets was found to be the same at 60≤energy intensity≤80 J/cm 2 and this may indicate that the same structural changes have happened. The track etch rate was found to be equal to the bulk etch rate for both sets, so the sensitivity is constant. In both sets several changes on the detector surfaces: tracks of different sizes and shapes and high density within the laser spot were observed. Out of the laser spot, the tracks become larger and lower density, indicating cross-linking and scission have happened, simultaneously, on the same surface as a result of UV-laser irradiation

  1. Lu-Hf geochronology on cm-sized garnets using microsampling: New constraints on garnet growth rates and duration of metamorphism during continental collision (Menderes Massif, Turkey)

    Science.gov (United States)

    Schmidt, Alexander; Pourteau, Amaury; Candan, Osman; Oberhänsli, Roland

    2015-12-01

    This study shows Lu-Hf geochronology of zoned garnet crystals contained in mica schists from the southern Menderes Massif, Turkey. Selected samples are four 3-5 cm large garnet megacrysts of which several consecutive garnet shells have been sampled with a micro-saw and analyzed for dating. The results are used to extract growth rates of garnet, and also to improve the time constraint for Alpine-aged overprint of the Pan-African basement in the Menderes Massif. Lu-Hf ages of the sampled garnet shells are determined by two-point garnet-only isochrons using the garnets' Lu-depleted rim compositions. This yields a consistent decrease of age information from core to rim segments of individual garnet crystals and the calculated isochron ages propose a time frame of growth between 42.6 ± 1.9 and 34.8 ± 3.1 Ma. Major element profiles in the investigated garnets characterize zoning patterns indicative of prograde conditions: Rayleigh fractionated bell-shaped Mn and decreasing Fe/(Fe + Mg) are recorded by the garnets' core to rim compositions. Therefore the obtained Lu-Hf ages record timing of early prograde growth for the cores of the garnets. Two of the large garnet crystals also yield isochron ages of 58.83 ± 0.69 and 50.16 ± 0.84 Ma in their innermost cores, which appear to record an early nucleation event. This view, however, is not in concordance with the observed major element profiles of these garnets, and therefore is interpreted with caution. Termination of the garnet growth period is determined through the calculation of radial growth rates based on the size of the garnets and the Lu-Hf ages obtained for consecutive shells. Extrapolation of these rates potentially constrains the total duration for garnet growth terminating at 31 ± 6 Ma. Comparison of the growth rates calculated for individual crystals shows a variety of slow and fast growing garnets, and similar results have been previously obtained with the Rb-Sr and Sm-Nd isotope systems. The new data

  2. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

    Science.gov (United States)

    Radmanesh, Mohammad; Rafiei, Zohreh

    2015-04-01

    The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

  3. Effects of tattoo ink's absorption spectra and particle size on cosmetic tattoo treatment efficacy using Q-switched Nd:YAG laser.

    Science.gov (United States)

    Leu, Fur-Jiang; Huang, Chuen-Lin; Sue, Yuh-Mou; Lee, Shao-Chen; Wang, Chia-Chen

    2015-01-01

    The mechanisms responsible for variable responses of cosmetic tattoos to Q-switched laser removal treatment remain unclear. We sought to investigate the properties of tattoo inks that may affect the efficacy of laser-assisted tattoo removal. The absorption of white, brown, and black inks before and after Q-switched neodymium-doped yttrium aluminum garnet laser irradiation were analyzed by a reflectance measurement system. Rats were tattooed using the three inks and treated with the same laser for two sessions. Skin biopsies were taken from the treated and untreated sites. Black ink showed strong absorption, reduced after laser irradiation, over the entire spectrum. White ink had low absorption over the visible light spectrum, and brown ink had strong absorption at 400-550 nm wavelengths. White and brown inks turned dark after laser exposure, and the absorption of laser-darkened inks were intermediate between their original color and black ink. White, brown, and black tattoos in rat skin achieved poor, fair to good, and excellent responses to laser treatment, respectively. Transmission electron microscopy showed that white tattoo particles were the largest, brown were intermediate, and black were the smallest before laser. After laser treatment, white and brown tattoo particles were mixtures of large and small particles, while black particles showed overall reduction in number and size. Black tattoo ink's excellent response to Q-switched lasers was associated with its strong absorption and small particle size. White tattoo ink's poor response was associated with its poor absorption, even after laser darkening, and large particle size.

  4. Shear bond strength and SEM morphology evaluation of different dental adhesives to enamel prepared with ER:YAG laser.

    Science.gov (United States)

    Pires, Patrícia T; Ferreira, João C; Oliveira, Sofia A; Azevedo, Alvaro F; Dias, Walter R; Melo, Paulo R

    2013-01-01

    Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching. Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values. One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I - 37% phosphoric acid (PA)+ ExciTE(®); Group II - ExciTE(®); Group III - AdheSE(®) self-etching; Group IV - FuturaBond(®) no-rinse. NR; Group V - Xeno(®) V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min. One-way ANOVA and post-hoc tests (P adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE(®) and ExciTE(®) without condition with PA. FuturaBond(®) NR and Xeno(®) V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used.

  5. A randomized, controlled, split-face clinical trial of 1320-nm Nd:YAG laser therapy in the treatment of acne vulgaris.

    Science.gov (United States)

    Orringer, Jeffrey S; Kang, Sewon; Maier, Lisa; Johnson, Timothy M; Sachs, Dana L; Karimipour, Darius J; Helfrich, Yolanda R; Hamilton, Ted; Voorhees, John J

    2007-03-01

    There is a need for additional effective treatments for acne vulgaris. Laser therapy has been explored as a therapeutic option for acne, but rigorously designed studies in this area have been limited. We sought to examine the efficacy of an infrared laser in the treatment of acne. We conducted a randomized, controlled, single-blind, split-face clinical trial of 46 patients with facial acne. Patients received a series of 3 nonablative laser treatments using a novel neodymium:yttrium-aluminum-garnet (Nd:YAG) laser to half of the face. Serial blinded lesion counts and global acne severity rating of standardized bilateral patient photographs were performed. Sebum production was measured, and patient self-assessment surveys were administered. A transient but statistically significant improvement in lesion counts of open comedones was demonstrated in treated skin as compared with untreated skin. There were no significant differences between treated and control sides of the face in terms of changes in mean papule or pustule counts. Grading of serial photographs revealed no significant differences between treated and untreated skin. Patient surveys indicated that the majority of patients found the treatments to be at least mildly effective for both acne and oiliness. The current study only addresses the efficacy of a single laser system employing a specific treatment regimen. Infrared laser therapy may improve comedonal acne. Additional work is needed to better define the degree and duration of the effect. Patients appear to positively view such therapy for both acne and oily skin.

  6. Characterization of ultrafine aluminum nanoparticles

    International Nuclear Information System (INIS)

    Sandstrom, Mary M.; Jorgensen, Betty S.; Mang, Joseph T.; Smith, Bettina L.; Son, Steven F.

    2004-01-01

    Aluminum nanopowders with particle sizes ranging from ∼25 nm to 80 nm were characterized by a variety of methods. We present and compare the results from common powder characterization techniques including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), BET gas adsorption surface area analysis, thermogravimetric analysis (TGA), photon correlation spectroscopy (PCS), and low angle laser light scattering (LALLS). Aluminum nanoparticles consist of an aluminum core with an aluminum oxide coating. HRTEM measurements of both the particle diameter and oxide layer thickness tend to be larger than those obtained from BET and TGA. LALLS measurements show a large degree of particle agglomeration in solution; therefore, primary particle sizes could not be determined. Furthermore, results from small-angle scattering techniques (SAS), including small-angle neutron (SANS) and x-ray (SAXS) scattering are presented and show excellent agreement with the BET, TGA, and HRTEM. The suite of analytical techniques presented in this paper can be used as a powerful tool in the characterization of many types of nanosized powders.

  7. Lasers

    CERN Document Server

    Milonni, Peter W

    1988-01-01

    A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear optics. Incorporates many intuitive explanations and practical examples. Discussions are self-contained in a consistent notation and in a style that should appeal to physicists, chemists, optical scientists and engineers.

  8. Microstructure and defect chemistry of yttrium aluminium garnet ceramics

    International Nuclear Information System (INIS)

    Schuh, L.H.

    1989-01-01

    This thesis describes basic aspects concerning the defect chemistry and the microstructure of yttrium aluminium garnet ceramics. The work consists of three parts: a literature study, an experimental part and a section giving computer simulation data of defects. (author). 320 refs.; 68 figs.; 72 schemes; 32 tabs

  9. Sol gel synthesis for preparation of yttrium aluminium garnet

    NARCIS (Netherlands)

    Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.; With, de G.; Terpstra, R.A.; Metselaar, R.

    1989-01-01

    Sol-gel—synthesis for preparation of pure yttrium aluminium garnet powder with small grain size is subject of this ongoing study. Starting materials were sulfates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3A1SO1Z) pH during hydrolysis as well as temperature during calcination and

  10. Static Magnetic Properties of AL800 Garnet Material

    Energy Technology Data Exchange (ETDEWEB)

    Kuharik, J. [Fermilab; Madrak, R. [Fermilab; Makarov, A. [Fermilab; Pellico, W. [Fermilab; Sun, S. [Fermilab; Tan, C. Y. [Fermilab; Terechkine, I. [Fermilab

    2017-05-17

    A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.

  11. Polyphase deformation and garnet growth in pelitic schists of Sausar ...

    Indian Academy of Sciences (India)

    metamorphism, minerals that do not participate in the metamorphic ... (internal schistosity – Si) and the matrix foliation .... region along the longer edges of the garnet con- firms that ..... Sarkar S N, Trivedi J R and Gopalan K 1986 Rb-Sr whole.

  12. Sol–gel preparation of selected lanthanide aluminium garnets

    Czech Academy of Sciences Publication Activity Database

    Dubnikova, N.; Garskaite, E.; Pinkas, J.; Bezdička, Petr; Beganskiene, A.; Kareiva, A.

    2010-01-01

    Roč. 55, č. 2 (2010), s. 213-219 ISSN 0928-0707 Institutional research plan: CEZ:AV0Z40320502 Keywords : lanthanide aluminium garnets * sol-gel processing Subject RIV: CA - Inorganic Chemistry Impact factor: 1.525, year: 2010

  13. High density Gd-substituted yttrium iron garnets by coprecipitation

    International Nuclear Information System (INIS)

    Lamastra, Francesca Romana; Bianco, Alessandra; Leonardi, Federica; Montesperelli, Giampiero; Nanni, Francesca; Gusmano, Gualtiero

    2008-01-01

    Gadolinium-substituted yttrium iron garnets are ferrite materials of primary importance in microwave engineering. Stoichiometric powders of nominal composition Y 2.6 Gd 0.4 Fe 5 O 12 (i.e. Fe/(Y + Gd) = 1.67) were prepared by reverse strike coprecipitation of metal nitrates. In order to investigate the influence of composition on phase formation, non-stoichiometric powders were also synthesised. On the basis of DTA/TGA analysis, dried coprecipitates were calcined between 600 deg. C and 1200 deg. C and then characterised by ICP, XRD and HT-XRD. Amorphous coprecipitates crystallise around 700 deg. C in cubic garnet phase along with small amounts of YFeO 3 and/or α-Fe 2 O 3 . Only iron-rich garnets, either pure or Gd-substituted, calcined at 1200 deg. C or above display a single-phase cubic garnet. According to thermal dilatometry results, calcined powders were sintered in air up to 1470 deg. C. The microstructure of sintered ceramics is made up of fine grains, the average size ranging between 3 μm and 13 μm. Density of sintered bodies ranged from 88% to 98%. Ferromagnetic resonance linewidth (ΔH -3dB ) ranged between 4352.9 A m -1 and 4392.7 A m -1 , depending on composition and microstructure

  14. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    International Nuclear Information System (INIS)

    Kryshtal, R.G.; Medved, A.V.

    2015-01-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined

  15. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    Energy Technology Data Exchange (ETDEWEB)

    Kryshtal, R.G.; Medved, A.V., E-mail: avm@ms.ire.rssi.ru

    2015-12-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined.

  16. Performance of Er:YAG laser ablation of hard bone under different irrigation water cooling conditions

    Science.gov (United States)

    Beltrán Bernal, Lina M.; Shayeganrad, Gholamreza; Kosa, Gabor; Zelechowski, Marek; Rauter, Georg; Friederich, Niklaus; Cattin, Philippe C.; Zam, Azhar

    2018-02-01

    The biological applicability of the Erbium-doped Yttrium Aluminum Garnet (Er:YAG) laser in surgical processes is so far limited to hard dental tissues. Using the Er:YAG laser for bone ablation is being studied since it has shown good performance for ablating dental hard tissues at the wavelength 2.94 μm, which coincides with the absorption peak of water, one of the main components of hard tissue, like teeth and bone. To obtain a decent performance of the laser in the cutting process, we aim at examining the influence of sequenced water jet irrigation on both, the ablation rate and the prevention of carbonization while performing laser ablation of bone with fixed laser parameters. An Er:YAG laser at 2.94 μm wavelength, 940 mJ energy per pulse, 400 μs pulse width, and 10 Hz repetition rate is used for the ablation of a porcine femur bone under different pulsed water jet irrigation conditions. We used micro-computed tomography (micro-CT) scans to determine the geometry of the ablated areas. In addition, scanning electron microscopy (SEM) is used for qualitative observations for the presence of carbonization and micro-fractures on the ablated surfaces. We evaluate the performance of the laser ablation process for the different water jet conditions in terms of the ablation rate, quantified by the ablated volume per second and the ablation efficiency, calculated as the ablated volume per pulse energy. We provide an optimized system for laser ablation which delivers the appropriate amount of water to the bone and consequently, the bone is ablated in the most efficient way possible without carbonization.

  17. Combined external-beam PIXE and {mu}-Raman characterisation of garnets used in Merovingian jewellery

    Energy Technology Data Exchange (ETDEWEB)

    Calligaro, T. E-mail: thomas.calligaro@culture.gouv.fr; Colinart, S.; Poirot, J.-P.; Sudres, C

    2002-04-01

    Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of 'cloisonne' style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, ...), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ('rhodolite'). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the 'rhodolite' garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, {mu}-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

  18. Management of a Recurrent Pyogenic Granuloma of the Hard Palate with Diode Laser: A Case Report.

    Science.gov (United States)

    Hasanoglu Erbasar, Güzin Neda; Senguven, Burcu; Gultekin, Sibel Elif; Cetiner, Sedat

    2016-01-01

    Pyogenic granuloma (PG) is a prevalent inflammatory hyperplasia of skin and oral mucosa which is often caused by constant low-grade local irritation, traumatic injury or hormonal factors. In many cases, gingival irritation and inflammation due to poor oral hygiene are precipitating factors. Oral PG occurs predominantly on the gingiva, but it is also encountered on the lips, tongue, buccal mucosa and rarely on the hard palate. Although surgical excision is the first choice of treatment, many other treatment modalities could be counted such as cryosurgery, sodium tetradecyl sulfate sclerotherapy, intralesional steroids, flash lamp pulsed dye laser, neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, carbon dioxide (CO2) laser, erbium-doped yttrium aluminum garnet (Er:YAG) lasers and diode laser have been suggested. After surgical excision recurrence occurs up to 16% of these lesions. It is believed that recurrence ensues as a result of incomplete excision, failure to eliminate etiologic factors or repeated trauma. A 50-year-old female was referred to the Department of Oral Surgery, Gazi University, School of Dentistry, complaining of a swelling and growth on the right side of the hard palate for four months. Patient reported a similar growth in the same area about two years earlier, which had turned out to be a PG by histopathology. The treatment plan included surgical excision of the lesion using diode laser. The patient reported no pain after the surgery. She was discharged with a prescription of chlorhexidine mouthwash and necessary post-operative instructions. At 7 days follow up visit, immediate recurrence of the lesion was observed, and it was excised by diode laser with 2 mm margins at its clinical periphery, to a depth up to the periosteum, by the same operator. No recurrence or scarring was observed in 14 months follow-up. Although diode laser is a secure and efficient technique for the treatment of intraoral PG, in order to minimize its recurrence, the

  19. Clinical evaluation of dentin hypersensitivity treatment with the low intensity Gallium-Aluminum-Arsenide laser - AsGaAl Avaliação clínica do tratamento da hiperestesia dentinária com laser de baixa potência de Arseniato de Gálio-Alumínio - AsGaAl

    Directory of Open Access Journals (Sweden)

    Luciana Chucre Gentile

    2004-12-01

    Full Text Available The dentin hypersensitivity is a painful condition rather prevalent in the general population. There are several ways of treatment for such condition, including the low intensity lasers. The proposal of this study was to verify the effectiveness of the Gallium-Aluminum-Arsenide diode laser in the treatment of this painful condition, using a placebo as control. MATERIALS AND METHODS: Thirty-two patients were selected, 22 females and 10 males, with ages ranging from 20 to 52 years old. The 32 patients were randomly distributed into two groups, treated and control; the sample consisted of 68 teeth, 35 in the treated group and 33 in the control group. The treated group was exposed to six laser applications with intervals from 48 to 72 hours, and the control group received, as placebo, applications of a curing light. RESULTS: A significant reduction was observed in the pain condition between the initial phase and after six laser applications; however, such reduction could also be observed for the control group exposed to the placebo. CONCLUSION: Therapy with the low intensity Gallium-Aluminum-Arsenide laser - AsGaAl induces a statistically significant reduction in the painful condition after each application and between the beginning and end of treatment, although there was no statistically significant difference between the treated group (laser and the control group (placebo at the end of treatment and after the mediate evaluation results (after 6 weeks, this way impairing the real measurement of laser effectiveness and placebo effect.A hiperestesia dentinária trata-se de uma condição dolorosa bastante prevalente nas populações mundiais. Várias são as modalidades de tratamento para tal condição, entre elas, os lasers de baixa potência. A proposta deste estudo foi a de verificar a efetividade do laser de diodo de Arseniato de Gálio-Alumínio no tratamento desta condição dolorosa, utilizando-se um placebo como controle. MATERIAIS E M

  20. Optical properties of color centers in calcium-stabilized gadolinium gallium garnets

    International Nuclear Information System (INIS)

    Pogatshnik, G.J.; Cain, L.S.; Chen, Y.; Evans, B.D.

    1991-01-01

    The addition of small amounts of calcium during the crystal growth of large-diameter, gadolinium gallium garnet (GGG) crystals creates color centers that absorb in the near-uv region of the spectrum. Ultraviolet and γ-ray irradiation of the crystals produced changes in the intensities of the uv color-center bands along with a broad absorption throughout the visible spectrum. The color center that gives rise to an absorption band at 350 nm serves as a photoionizable donor center so that uv excitation results in a visible coloration of the crystals. The effects of oxidation and reduction treatments on the strength of the color-center bands and on the radiation response of the material were examined. Photoluminescence bands were observed in both reduced GGG crystals as well as crystals that were irradiated with neutrons. Visible coloration is likely to occur during flashlamp pumping of laser rods that utilize large-diameter GGG crystals as the laser host. The changes in the optical properties of the material under uv excitation indicate that the addition of small amounts of calcium to assist in the growth of large-diameter crystals is likely to result in the degradation of laser performance

  1. Mapping the Topography of Mercury with MESSENGER Laser Altimetry

    Science.gov (United States)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Smith, David E..; Zubor, Maria T.

    2012-01-01

    The Mercury Laser Altimeter onboard MESSENGER involves unique design elements that deal with the challenges of being in orbit around Mercury. The Mercury Laser Altimeter (MLA) is one of seven instruments on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. MESSENGER was launched on 3 August 2004, and entered into orbit about Mercury on 18 March 2011 after a journey through the inner solar system. This involved six planetary flybys, including three of Mercury. MLA is designed to map the topography and landforms of Mercury's surface. It also measures the planet's forced libration (motion about the spin axis), which helps constrain the state of the core. The first science measurements from orbit taken with MLA were made on 29 March 2011 and continue to date. MLA had accumulated about 8.3 million laser ranging measurements to Mercury's surface, as of 31 July 2012, i.e., over six Mercury years (528 Earth days). Although MLA is the third planetary lidar built at the NASA Goddard Space Flight Center (GSFC), MLA must endure a much harsher thermal environment near Mercury than the previous instruments on Mars and Earth satellites. The design of MLA was derived in part from that of the Mars Orbiter Laser Altimeter on Mars Global Surveyor. However, MLA must range over greater distances and often in off-nadir directions from a highly eccentric orbit. In MLA we use a single-mode diode-pumped Nd:YAG (neodymium-doped yttrium aluminum garnet) laser that is highly collimated to maintain a small footprint on the planet. The receiver has both a narrow field of view and a narrow spectral bandwidth to minimize the amount of background light detected from the sunlit hemisphere of Mercury. We achieve the highest possible receiver sensitivity by employing the minimum receiver detection threshold.

  2. Experimental Study of The Physical Properties of The Laser Diode (AlGaAs/GaAs) (Arsenic Gallium Aluminum) To Use as a Pumping Source of Laser Nd:YAG

    International Nuclear Information System (INIS)

    Dayoub, N.; Altwel, E.

    2009-01-01

    The research includes an experimental study of the physical properties of the laser diode (AlGaAs/GaAs). We have made a detailed display of the structure of diode and mechanism of its operation, as well as its convenience as a pumping source for Solid-state laser Nd:YAG. Then we studied the changes of potential difference (expressing the capacity of laser diode) by the dependence of diode temperature, for variant intensity of the injection current, and the changes of potential by dependence of the injection current; and finally, we made a study of the capacity of laser diode output by dependence of the injection current. (author)

  3. ALUMINUM BOX BUNDLING PRESS

    Directory of Open Access Journals (Sweden)

    Iosif DUMITRESCU

    2015-05-01

    Full Text Available In municipal solid waste, aluminum is the main nonferrous metal, approximately 80- 85% of the total nonferrous metals. The income per ton gained from aluminum recuperation is 20 times higher than from glass, steel boxes or paper recuperation. The object of this paper is the design of a 300 kN press for aluminum box bundling.

  4. The Efficacy and Safety of Ablative Fractional Resurfacing Using a 2,940-Nm Er:YAG Laser for Traumatic Scars in the Early Posttraumatic Period

    Directory of Open Access Journals (Sweden)

    Sun Goo Kim

    2012-05-01

    Full Text Available Background Skin injuries, such as lacerations due to trauma, are relatively common, andpatients are very concerned about the resulting scars. Recently, the use of ablative and nonablativelasers based on the fractional approach has been used to treat scars. In this study,the authors demonstrated the efficacy and safety of ablative fractional resurfacing (AFRfor traumatic scars using a 2,940-nm erbium: yttrium-aluminum-garnet (Er:YAG laser fortraumatic scars after primary repair during the early posttraumatic period.Methods Twelve patients with fifteen scars were enrolled. All had a history of faciallaceration and primary repair by suturing on the day of trauma. Laser therapy was initiatedat least 4 weeks after the primary repair. Each patient was treated four times at 1-monthintervals with a fractional ablative 2,940-nm Er:YAG laser using the same parameters. Posttreatmentevaluations were performed 1 month after the fourth treatment session.Results All 12 patients completed the study. After ablative fractional laser treatment, alltreated portions of the scars showed improvements, as demonstrated by the VancouverScar Scale and the overall cosmetic scale as evaluated by 10 independent physicians, 10independent non-physicians, and the patients themselves.Conclusions This study shows that ablative fractional Er:YAG laser treatment of scars reducesscars fairly according to both objective results and patient satisfaction rates. The authorssuggest that early scar treatment using AFR can be one adjuvant scar management methodfor improving the quality of life of patients with traumatic scars.

  5. The Friningen Garnet Peridotite (central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite

    NARCIS (Netherlands)

    Gilio, Mattia; Clos, Frediano; van Roermund, Herman L M|info:eu-repo/dai/nl/068882432

    2015-01-01

    We present pseudosections of Cr-bearing garnet peridotite that together with new mineral–chemical data allow quantification of the early PT conditions of the original lithospheric mantle assemblage (M1) of the Friningen Garnet Peridotite (FGP) located in the central/middle belt of the Seve Nappe

  6. Structure and scintillation yield of Ce-doped Al–Ga substituted yttrium garnet

    International Nuclear Information System (INIS)

    Sidletskiy, Oleg; Kononets, Valerii; Lebbou, Kheirreddine; Neicheva, Svetlana; Voloshina, Olesya; Bondar, Valerii; Baumer, Vyacheslav; Belikov, Konstantin; Gektin, Alexander; Grinyov, Boris; Joubert, Marie-France

    2012-01-01

    Highlights: ► Range of Y 3 (Al 1−x Ga x ) 5 O 12 :Ce solid solution crystals are grown from melt by the Czochralski method. ► Light yield of mixed crystals reaches 130% of the YAG:Ce value at x ∼ 0.4. ► ∼1% of antisite defects is formed in YGG:Ce, but no evidence of this is obtained for the rest of crystals. -- Abstract: Structure and scintillation yield of Y 3 (Al 1−x Ga x ) 5 O 12 :Ce solid solution crystals are studied. Crystals are grown from melt by the Czochralski method. Distribution of host cations in crystal lattice is determined. Quantity of antisite defects in crystals is evaluated using XRD and atomic emission spectroscopy data. Trend of light output at Al/Ga substitution in Y 3 (Al 1−x Ga x ) 5 O 12 :Ce is determined for the first time. Light output in mixed crystals reaches 130% comparative to Ce-doped yttrium–aluminum garnet. Luminescence properties at Al/Ga substitution are evaluated.

  7. Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

    Science.gov (United States)

    Barickman, M. H.; Martin, C.; Flores, K. E.; Harlow, G. E.; Bonnet, G.

    2016-12-01

    The Guatemala Suture Zone (GSZ) is situated in central Guatemala, between the North American and Caribbean plates. Two serpentinite mélanges straddle the Motagua Fault system: the North Motagua Mélange (NMM) and the South Motagua Mélange (SMM). In this study, chemically zoned garnet grains from four eclogite blocks from the NMM were analyzed by EMPA for major elements and LA-ICP-MS for trace elements to unravel the geological history of the eclogites. These eclogites typically consist of euhedral to subhedral garnets, partly retrogressed omphacite grains, and accessory minerals such as phengite and epidote as inclusions in garnet. EBSD was employed to examine apparent garnet inclusions in garnet. The garnet grains in NMM eclogites display complex chemical zonations: all grains roughly show a spessartine-rich core, an almandine-rich core and/or intermediate zone, and a pyrope and grossular-rich rim. Additionally, crystal resorption can be observed between the different zones, and the pyrope-grossular rim can display oscillatory zoning. Finally, grossular-rich zones (crystallographically syntactic) within garnet are present in all studied samples. REE and spider diagrams do not show any significant difference in the patterns of the different zones within the garnet, or indicating that the chemical environment from which each garnet zone grew was broadly the same. The lack of significant variation in LILE content indicates that a fluid influx during garnet growth is unlikely. Consequently, we interpret that garnet grains grew in a largely closed system; however, the presence of the grossular-rich zones, argues for occasional excursions into conditions when either two garnets crystallized or Ca-rich overgrowths that were largely resorbed prior to subsequent continued garnet growth.

  8. Laser and Light Treatments for Hair Reduction in Fitzpatrick Skin Types IV-VI: A Comprehensive Review of the Literature.

    Science.gov (United States)

    Fayne, Rachel A; Perper, Marina; Eber, Ariel E; Aldahan, Adam S; Nouri, Keyvan

    2018-04-01

    Unwanted facial and body hair presents as a common finding in many patients, such as females with hirsutism. With advances in laser and light technology, a clinically significant reduction in hair can be achieved in patients with light skin. However, in patients with darker skin, Fitzpatrick skin types (FST) IV-VI, the higher melanin content of the skin interferes with the proposed mechanism of laser-induced selective photothermolysis, which is to target the melanin in the hair follicle to cause permanent destruction of hair bulge stem cells. Many prospective and retrospective studies have been conducted with laser and light hair-removal devices, but most exclude patients with darkly pigmented skin, considering them a high-risk group for unwanted side effects, including pigmentation changes, blisters, and crust formation. We reviewed the published literature to obtain studies that focused on hair reduction for darker skin types. The existing literature for this patient population identifies longer wavelengths as a key element of the treatment protocol and indicates neodymium-doped yttrium aluminum garnet (Nd:YAG), diode, alexandrite, and ruby lasers as well as certain intense pulsed light sources for safe hair reduction with minimal side effects in patients with FST IV-VI, so long as energy settings and wavelengths are appropriate. Based on the findings in this review, safe and effective hair reduction for patients with FST IV-VI is achievable under proper treatment protocols and energy settings.

  9. Effect of Nd:YAG and Diode Lasers on Apical Seal of Root Canals Filled with AH Plus and Mineral Trioxide Aggregate-Based Sealers

    Directory of Open Access Journals (Sweden)

    Elham Khoshbin

    2018-01-01

    Full Text Available Objectives: Laser irradiation, as an adjunct to root canal preparation, may increase the success rate of endodontic treatments. This study aimed to assess the effect of neodymium-doped yttrium aluminum garnet (Nd:YAG and diode lasers on the apical seal of the root canals filled with AH Plus® and mineral trioxide aggregate (MTA-based sealers.Materials and Methods: This in-vitro experimental study was conducted on 96 single-rooted, single-canal extracted human teeth with closed apices. The root canals were prepared by using ProTaper® rotary instruments and were randomly divided into six groups (n=16: 940-nm diode laser and AH Plus® sealer (group 1, Nd:YAG laser and AH Plus® sealer (group 2, AH Plus® sealer (group 3, 940-nm diode laser and MTA-based sealer (group 4, Nd:YAG laser and MTA-based sealer (group 5, MTA-based sealer (group 6, as well as positive and negative control groups. A bacterial leakage model was used for microleakage assessment. Qualitative assessment was done by using a scanning electron microscope (SEM. Data were analyzed by two-way analysis of variance (ANOVA at the significance level of 0.05.Results: There were statistically significant differences between the experimental and control groups (P=0.002. The laser-treated groups showed a lower apical microleakage compared to the non-laser-treated groups, although the difference was not statistically significant (P>0.05. No significant differences were noted between the two lasers in terms of the apical microleakage, irrespective of the type of sealer (P>0.05.Conclusions: Laser irradiation, as an adjunct to root canal preparation, has no significant effect on the level of apical microleakage.

  10. Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

    Science.gov (United States)

    Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei

    2015-02-01

    This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

  11. Effect of Er:YAG laser irradiation on bonding property of zirconia ceramics to resin cement.

    Science.gov (United States)

    Lin, Yihua; Song, Xiaomeng; Chen, Yaming; Zhu, Qingping; Zhang, Wei

    2013-12-01

    This study aimed to investigate whether or not an erbium: yttrium-aluminum-garnet (Er:YAG) laser could improve the bonding property of zirconia ceramics to resin cement. Surface treatments can improve the bonding properties of dental ceramics. However, little is known about the effect of Er:YAG laser irradiated on zirconia ceramics. Specimens of zirconia ceramic pieces were made, and randomly divided into 11 groups according to surface treatments, including one control group (no treatment), one air abrasion group, and nine Er:YAG laser groups. The laser groups were subdivided by applying different energy intensities (100, 200, or 300 mJ) and irradiation times (5, 10, or 15 sec). After surface treatments, ceramic pieces had their surface morphology observed, and their surface roughness was measured. All specimens were bonded to resin cement. Shear bond strength was measured after the bonded specimens were stored in water for 24 h, and additionally aged by thermocycling. Statistical analyses were performed using one way analysis of variance (ANOVA) and Tukey's test for shear bond strength, and Dunnett's t test for surface roughness, with α=0.05. Er:YAG laser irradiation changed the morphological characteristics of zirconia ceramics. Higher energy intensities (200, 300 mJ) could roughen the ceramics, but also caused surface cracks. There were no significant differences in the bond strength between the control group and the laser groups treated with different energy intensities or irradiation times. Air abrasion with alumina particles induced highest surface roughness and shear bond strength. Er:YAG laser irradiation cannot improve the bonding property of zirconia ceramics to resin cement. Enhancing irradiation intensities and extending irradiation time have no benefit on the bond of the ceramics, and might cause material defect.

  12. RBS Characterization of Yttrium Iron Garnet Thin Films

    International Nuclear Information System (INIS)

    Roumie, M; Abdel samad, B.

    2008-01-01

    Magnetic materials such as yttrium iron garnet (YIG) are of great importance for its magneto-optic properties and for their potential applications in the domain of optical telecommunications. The deposition of thin films of YIG, on quartz or GGG (gadolinium gallium garnet) substrate, was performed using radio frequency non reactive magnetron sputtering, followed by high temperature annealing which is needed to enhance the crystallinity of the layers. Rutherford backscattering spectrometry RBS was used to determine the thickness and stoichiometry of the performed layers in order to investigate correlations between growth conditions and the quality of the final material. RBS measurements showed the influence of the deposition time and the temperature substrate on the film growth and its stoichiometry. (author)

  13. Coercive force features in stressed epitaxial ferrite-garnet films

    International Nuclear Information System (INIS)

    Dubinko, S.V.; Nedviga, A.S.; Vishnevskij, V.G.; Shaposhnikov, A.N.; Yagupov, V.S.; Nesteruk, A.G.; Prokopov, A.R.

    2005-01-01

    One has investigated into effect of a relative mismatching of periods of lattices of a film and of a substrate within 0.5-0.85% range on behavior of the coercive force of (Bi, Sm, Lu, Ca) 3 (Fe, Sc, Ga, Al) 5 O 12 composition ferrite garnet epitaxial films (FGEF) synthesized at (111) orientation gadolinium-gallium garnet substrates. One has revealed that the FGEF coercive force at increase of the relative mismatching of periods of lattices of a film and of a substrate increases at first, while when reaching the maximum value it begins to decrease. The coercive force maximum value is shown to result from the periodical localized stresses. The period of the localized stresses is determined by the value of mismatching of periods of lattices of a film and of a substrate [ru

  14. Low temperature delayed recombination decay in scintillating garnets

    Czech Academy of Sciences Publication Activity Database

    Mihóková, Eva; Babin, Vladimir; Bartosiewicz, Karol; Schulman, L. S.; Čuba, V.; Kučera, M.; Nikl, Martin

    2015-01-01

    Roč. 40, Fešb (2015), s. 127-131 ISSN 0925-3467 R&D Projects: GA ČR GA13-09876S EU Projects: European Commission(XE) 316906 - LUMINET Grant - others:AVČR(CZ) M100101212 Institutional support: RVO:68378271 Keywords : luminescence * garnets * scintillator * tunneling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  15. Study of RE-garnets using BPW method

    Science.gov (United States)

    Goveas, Neena; Mukhopadhyay, P.; Mukhopadhyay, G.

    1995-02-01

    The magnetic susceptibility of rare-earth (Y and Lu) iron garnets is studied using a modified Bethe-Peierls-Weiss (BPW) approximation. The modifications enable us to incorporate the three exchange parameters Jad, Jaa and Jdd necessary to describe the systems. We get excellent fits to the experimental susceptibilities from which we determined the J-values. These also give excellent agreement with the spin wave dispersion relation constant D.

  16. Spray and microjets produced by focusing a laser pulse into a hemispherical drop

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2009-11-02

    We use high-speed video imaging to study laser disruption of the free surface of a hemispheric drop. The drop sits on a glass surface and the Nd:YAG (yttrium aluminum garnet) laser pulse propagates through the drop and is focused near the free surface from below. We focus on the evolution of the cylindrical liquid sheet and spray which emerges out of the drop and resembles typical impact crowns. The tip of the sheet emerges at velocities over 1 km/s. The tip of the crown breaks up into fine spray some of which is sucked back into the growing cavity at about 100 m/s. We measure the size of the typical spray droplets to be about 3 μm. We also show the formation of fine microjets, which are produced when the laser is focused inside the drop and the shock front hits small bubbles sitting under the free surface. For water these microjets are 5–50 μm in diameter and exit at 100–250 m/s. For higher viscositydrops, these jets can emerge at over 500 m/s.

  17. Heat treatment of transparent Yb:YAG and YAG ceramics and its influence on laser performance

    Science.gov (United States)

    Fujioka, Kana; Mochida, Tetsuo; Fujimoto, Yasushi; Tokita, Shigeki; Kawanaka, Junji; Maruyama, Momoko; Sugiyama, Akira; Miyanaga, Noriaki

    2018-05-01

    Composite transparent ceramic materials are promising for improving the performance of high-average-power lasers. A combination of room-temperature bonding via surface treatment by a fast atom beam and diffusion bonding via heating, which effectively controls the ion diffusion distance near the interface, makes the laser materials suitable for a variety of oscillator/amplifier. During the heat treatment of yttrium aluminum garnet (YAG) ceramics, the Si ions in the solid solution of the sintering aid incorporated within the grains were seen to segregate at the grain boundary, resulting in an increase of scattering sites. The number density and size of the scattering sites strongly depended on the post-heating temperature rather than the heating time. Specifically, heating at 1300 °C did not affect the transmittance of the YAG ceramic, whereas both the size and number of scattering sites substantially increased with a heat treatment at 1400 °C. The laser oscillation experiment using cryogenically-cooled Yb:YAG ceramics exhibited heating temperature dependence of the slope efficiency owing to the increasing scattering loss.

  18. Spray and microjets produced by focusing a laser pulse into a hemispherical drop

    KAUST Repository

    Thoroddsen, Sigurdur T; Takehara, K.; Etoh, T. G.; Ohl, C.-D.

    2009-01-01

    We use high-speed video imaging to study laser disruption of the free surface of a hemispheric drop. The drop sits on a glass surface and the Nd:YAG (yttrium aluminum garnet) laser pulse propagates through the drop and is focused near the free surface from below. We focus on the evolution of the cylindrical liquid sheet and spray which emerges out of the drop and resembles typical impact crowns. The tip of the sheet emerges at velocities over 1 km/s. The tip of the crown breaks up into fine spray some of which is sucked back into the growing cavity at about 100 m/s. We measure the size of the typical spray droplets to be about 3 μm. We also show the formation of fine microjets, which are produced when the laser is focused inside the drop and the shock front hits small bubbles sitting under the free surface. For water these microjets are 5–50 μm in diameter and exit at 100–250 m/s. For higher viscositydrops, these jets can emerge at over 500 m/s.

  19. Wear performance of garnet aluminium composites at high contact pressure

    Science.gov (United States)

    Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

    2016-05-01

    To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

  20. Magnetic anisotropies in ultrathin bismuth iron garnet films

    International Nuclear Information System (INIS)

    Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric

    2013-01-01

    Ultrathin bismuth iron garnet Bi 3 Fe 5 O 12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi 3 Fe 5 O 12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi 3 Fe 5 O 12 films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi 3 Fe 5 O 12 were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed

  1. Magnetic anisotropies in ultrathin bismuth iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

    2013-06-15

    Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

  2. Graphene-aluminum nanocomposites

    International Nuclear Information System (INIS)

    Bartolucci, Stephen F.; Paras, Joseph; Rafiee, Mohammad A.; Rafiee, Javad; Lee, Sabrina; Kapoor, Deepak; Koratkar, Nikhil

    2011-01-01

    Highlights: → We investigated the mechanical properties of aluminum and aluminum nanocomposites. → Graphene composite had lower strength and hardness compared to nanotube reinforcement. → Processing causes aluminum carbide formation at graphene defects. → The carbides in between grains is a source of weakness and lowers tensile strength. - Abstract: Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

  3. Experience with endoscopic holmium laser in the pediatric population

    Science.gov (United States)

    Merguerian, Paul A.; Reddy, Pramod P.; Barrieras, Diego; Bagli, Darius J.; McLorie, Gordon A.; Khoury, Antoine E.

    1999-06-01

    Introduction: Due to the unavailability of suitable endoscopic instruments, pediatric patients have not benefited fully from the technological advances in the endoscopic management of the upper urinary tract. This limitation may be overcome with the Holmuim:Yttrium-Aluminum-Garnet(Ho:YAG) laser delivered via small instruments. To date, there is no published report on the use of this modality in children. Purpose: We evaluated the indications, efficacy, and complications of endourological Ho:YAG laser surgery in the treatment of pediatric urolithiasis, posterior urethral valves, ureterocele and ureteropelvic junction obstruction. Methods: The patient population included 10 children with renal, ureteral and bladder calculi, 2 children with posterior urethral valves, 2 children with obstructing ureteroceles, 2 children with ureteropelvic junction obstruction and 1 child with a urethral stricture. Access to the lesions was either antegrade via a percutaneous nephrostomy tract or retrograde via the urethra. A solid state Ho:YAG laser with maximum output of 30 watts (New Star lasers, Auburn, CA) was utilized as the energy source. Results: A total of 10 patients underwent laser lithotripsy. The means age of the patients was 9 yrs (5-13 yrs). The average surface area of the calculi as 425.2 mm2 (92-1645 mm2). 8 of the patients required one procedure to render them stone free, one patient had a staghorn calculus filling every calyx of a solitary kidney requiring multiple treatments and one other patient with a staghorn calculus required 2 treatments. There were no complications related to the laser lithotripsy. Two newborn underwent successful ablation of po sterious urethral valves. Two infants underwent incision of obstructing ureteroceles with decompression of the ureterocele on postoperative ultrasound. Two children underwent endypyelotomy for ureteropelvic junction obstruction. One was successful an done required an open procedure to correct the obstruction. One child

  4. In Situ Measurements of the Post-Spinel and Post-Garnet Phase Boundaries in Pyrolite at 17-32 GPa and 1500-2400 K

    Science.gov (United States)

    Ye, Y.; Gu, C.; Shim, S. H.; Prakapenka, V.; Meng, Y.

    2014-12-01

    Recent seismic studies have revealed complex structures near 660-km depth. In order to understand the effects of composition and temperature, we measured the depth and Clapeyron slope of the post-spinel and post-garnet boundaries at the pressure-temperature conditions of 600-700 km depths in pyrolitic compositions: (1) MgO-Al2O3-SiO2 (MAS) and (2) CaO-MgO-Al2O3-SiO2-FeO (CMASF). Glass starting materials were mixed with either gold or platinum powder (10 wt%) for laser coupling and internal pressure scale. Cold compressed foils of the mixtures were loaded in the diamond-anvil cell together with Ar or KCl for thermal insulation and pressure transmission. X-ray diffraction patterns were measured for the samples in the diamond-anvil cell at in situ high pressure and high temperature combined with double side laser heating at beamlines 13-IDD (GSECARS) and 16-IDB (HPCAT) in the Advanced Photon Source. Within 5 to 8 minutes of heating, stable crystalline phase assemblages were formed and persisted with further heating for 20 to 30 minutes. A total of 160 heating cycles were conducted at different pressures and temperatures, providing tight constrains on the phase boundaries. Our data show that the post-spinel transition occurs at 23.6-24.5 GPa and 1850 K with a Clapeyron slope of -2.5(4) MPa/K if the Pt pressure scales are used, consistent with the seismic observation of the 660 discontinuity. The post-garnet boundary occurs at 24.2-27.5 GPa and 1900 - 2450 K. We found that the Clapeyron slope of the post-garnet transition increases with Fe: from 2.4 MPa/K for MAS to 6.2 MPa/K for CMASF. Below 1900 K, garnet disappears near the post-spinel boundary within the resolution of our measurements. Our new data supports the notion that the 660 discontinuity is dominated by the post-spinel phase transition below 1900 K while dominated by the post-garnet phase transition above 1900 K. However, our data indicate much larger Clapeyron slope of the post-garnet transition, suggesting

  5. A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

    Science.gov (United States)

    Lippert, Julia F; Lacey, Steven E; Lopez, Ramon; Franke, John; Conroy, Lorraine; Breskey, John; Esmen, Nurtan; Liu, Li

    2014-01-01

    The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants.

  6. Fluid-aided incorporation of Y into almandine-pyrope garnet via coupled dissolution-reprecipitation

    Science.gov (United States)

    Harlov, D. E.

    2009-12-01

    In nature almandine-pyrope garnet is a well-known host for a variety of trace elements including (Y+HREE), Sr, HFSE, as well as LREE such as Sm and Nd; all of which have important roles with regard to various geological processes (Kohn, 2009, GCA, 73, 170). For example, Y exchange between xenotime and garnet has been empirically calibrated as a geothermometer (Pyle and Spear, 2000, CMP, 138, 51). Sm/Nd and Lu/Hf dating, using garnet, is a well-known geochronometer (Thöni et al., 2008, Chem Geol, 254, 216). In general, REE + HFSE + Sr have been used to chart garnet growth and subsequently the evolution of the host rock (Konrad-Schmolke et al., 2008, EPSL, 272, 488). Incorporation of Y into garnet is probably the most widely studied trace element. These studies range from stress-induced redistribution of Y in garnet (Røhr et al, 2007, Am Mineral, 92, 1276) to Y zoning during garnet growth (Zeh, 2005, J Petrol, 47, 2335). While the incorporation of Y into garnet has generally been thought to occur either via diffusion or during garnet growth, more recent workers have suggested that incorporation of Y could also be fluid-aided. Fluid-aided incorporation of Y into garnet has been tested in the piston-cylinder apparatus (CaF2 assemblies, cylindrical graphite ovens) at 1000 MPa and 900 °C (8 days duration). Here, 10 mg of 50-200 µm size, inclusion-free, gem quality, fragments of the Gore Mountain garnet (Alm40-49, Py37-43, Gr13-16, Sp1) plus 5 mg 2N NaOH and 2 mg Y2O3 were loaded into a 3 mm diameter, 1 cm long, Au capsule that was then arc-welded shut and placed vertically in the CaF2 assembly such that the NiCr thermocouple tip came halfway up along the Au capsule length. Examination of the garnet fragments after the experiment indicates both high Y mobility and the partial alteration of the garnet in the form of a remobilized Y3Al5O12 component enriching those areas of the garnet along the grain rim. The enriched areas take the form of a series of intergrowths with

  7. Broadband Near-Infrared Quantum Cutting in Metal-Ion Codoped Y3Al5O12 Thin Films Grown by Pulsed-Laser Deposition for Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Mei Kwan Lau

    2013-01-01

    Full Text Available We have deposited thin films of yttrium aluminum garnet (YAG doped with Ce3+ and Yb3+ on quartz and silicon substrates by pulsed laser deposition. Near-infrared (NIR quantum cutting which involves the emission of NIR photons through the downconversion from Ce3+ to Yb3+ is realized. Upon the broadband excitation of Ce3+ ions with a visible photon at the peak wavelength of 450 nm, NIR photons are generated by Yb3+ ions, with an emission wavelength centered at 1030 nm. The luminescent decay curves of Ce3+ were recorded as a supporting evidence corresponding to the energy transfer. This work offers a better and more convenient approach compatible with crystalline silicon solar cell compared to conventional bulk phosphors.

  8. Numerical simulation of heat transfer and fluid flow during double-sided laser beam welding of T-joints for aluminum aircraft fuselage panels

    Science.gov (United States)

    Yang, Zhibin; Tao, Wang; Li, Liqun; Chen, Yanbin; Shi, Chunyuan

    2017-06-01

    In comparison with conventional laser beam welding, double-sided laser beam welding has two laser heat sources simultaneously and symmetrically loaded from both sides makes it to be a more complicated coupled heat transport and fluid flow process. In this work, in order to understand the heat transfer and fluid flow, a three-dimensional model was developed and validated with the experimental results. The temperature field, fluid flow field, and keyhole characteristic were calculated using the developed model by FLUENT software. Calculated results indicated that the temperature and fluid flow fields were bilateral symmetry along the stringer center, and the molten pool maximum length was located near the keyhole intersection position. The skin side had higher temperature and faster cooling speed. Several characteristic flow patterns in the weld pool cross section, including the vortexes flows near the keyhole opening position, the convection flows above the keyhole intersection location, the regularity downward flows at the molten pool bottom. And in the lengthwise section, a distinct vortex flow below the keyhole, and the liquid metal behind the keyhole first flowed to near the molten pool maximum length location and then to the molten pool surface. Perpendicular to and along welding direction the keyhole liquid metal flowed to the weld molten pool surface and around the keyhole, respectively. The special temperature fields and fluid flow patterns were closely related to the effects of the double sides' laser energy coupling and enhancement. The calculated weld pool geometry basically in good agreement with the experimental results indicated that the developed model was validity and reasonable.

  9. Insights into the mantle geochemistry of scandium from a meta-analysis of garnet data

    Science.gov (United States)

    Chassé, Mathieu; Griffin, William L.; Alard, Olivier; O'Reilly, Suzanne Y.; Calas, Georges

    2018-06-01

    The meta-analysis of about 13,000 analyses of scandium content in garnet grains shows that, below the spinel-garnet transition, this phase carries about three-quarters of the Sc budget of the mantle, indicating its control on Sc mobility. The Sc content of garnets in mafic rocks is low, due to a dilution effect resulting from their high modal content in garnet. Garnets from ultramafic rocks exhibit a wider range of Sc concentrations. We assess the relative influence of thermobarometry, crystal chemistry and fluid-related events on the distribution of Sc in garnet from such rocks to improve the tracking of geochemical processes in the mantle. Pressure and temperature of equilibration in the mantle are second-order factors influencing the Sc content of garnet, while crystal chemistry, in particular Cr/Cr+Al and Ca/Ca+Mg, is the main parameter controlling the compatibility of Sc. Scandium is incorporated in both X and Y sites of Cr-Ca-rich garnets, resulting in a behaviour intermediate between rare-earth elements, incorporated in the X site, and trivalent transition elements, occupying the Y site. This affinity for both sites results in a mild compatibility of Sc in the garnet stability field of the mantle; hence Sc concentration in garnet increases with melt extraction and can be reduced by silicate-melt metasomatism. In contrast, metasomatism by volatile-rich fluids increases the Sc concentration in garnet. The control of garnet on the compatibility of Sc in deep lithospheric rocks demonstrates the potential of using Sc to track the conditions of formation of magmas and their residual rocks, as well as the origin and nature of metasomatic fluids.

  10. Synthesis of complex oxides with garnet structure by spray drying of an aqueous salt solution

    Science.gov (United States)

    Makeenko, A. V.; Larionova, T. V.; Klimova-Korsmik, O. G.; Starykh, R. V.; Galkin, V. V.; Tolochko, O. V.

    2017-04-01

    The use of spray drying to obtain powders of complex oxides with a garnet structure has demonstrated. The processes occurring during heating of the synthesized oxide-salt product, leading to the formation of a material with a garnet structure, have been investigated using DTA, TGA, XPS, and XRD. It has been shown that a single-phase garnet structure of system (Y x Gd(3- x))3Al5O12 can be synthesized over the entire range of compositions.

  11. Research in garnet crystal (GSGG) development. Final report, 1 May 1984-31 December 1984

    International Nuclear Information System (INIS)

    Belt, R.F.; Uhrin, R.; Vemuri, K.

    1985-01-01

    This program describes the crystal growth of neodymium and chromium doped simultaneously into the host crystal of gadolinium scandium gallium garnet (Nd 3+ , Cr 3 +:Gd 3 (Sc,Ga) 2 Ga 3 O 12 or Nd,Cr:GSGG). Ten experimental boules were grown by the Czochralski method at a diameter of 1.0-1.2 inch. Special attention was given to congruently melting compositions, the Nd and Cr content, growth rate, atmosphere of growth, control of the solid liquid interface, and boule orientation. For each of our crystals a (0.25 x 3.00) inch cylindrical laser rod was extracted, fabricated, tested passively, and delivered to the Lawrence Livermore National Laboratory for active testing. At the same time, boule samples were examined for optical absorption, loss at 1.06μm, refractive index birefringence, and other physical properties. Results have demonstrated that optical quality can approach that of Nd:YAG in rod form. The increased efficiency of Nd,Cr:GSGG was confirmed to be about 2 times that of Nd:YAG. We also show that 2 inch diameter crystal boules can be grown successfully. It appears that larger boules are feasible for slab laser experiments

  12. Mineral chemistry of garnet in pegmatite and metamorphic rocks in the Hamedan area

    Directory of Open Access Journals (Sweden)

    Ahmad Ahmadi Khalaji

    2015-10-01

    Full Text Available Introduction The area of this study is located near Hamadan within the Sanandaj - Sirjan tectonic zone. In the Hamadan area, consisting mainly of Mesozoic plutonic and metamorphic rocks, aplites and pegmatites locally contain garnets.(Baharifar et al., 2004, Amidi and Majidi, 1977; Torkian, 1995. Garnet-bearing schists and hornfelses in the area are products of regional metamorphism shown by slate and phyllite (Baharifar, 2004. In this investigation the distribution of elements in garnet in different rock type was studied to determine their mineral types and conditions of formation. Garnet samples from igneous and metamorphic rocks were analyzed by electron microprobe (EMPA, the results of which are presented in this article. Materials and methods Thirty-five samples were selected for thin section preparation and twenty thin-polished sections were prepared for mineralogical and microprobe analysis. Thin sections of garnet-bearing igneous (pegmatite and metamorphic rocks (schist and hornfels were studied by polarizing microscope. Chemical analysis was performed on the garnets (38 points using a Caimeca SX100 electron microprobe at an acceleration voltage of 15 kV and electric current of 15 nA in the Mineral Processing Research Center, Iran. Separation of iron (II and Fe (III was calculated by Droop’s method (1987 and the structural formulas of the garnets were calculated using 24 oxygens to determine the relative proportions of the end-members using the mineral spreadsheet software of Preston and Still (2001. Results Based on the analyses, almandine (Fe - Al garnet and spessartine (Mn - Al garnet are the principal types of the (Kamari metamorphic and (Abaro pegmatitic garnets, that belong to the well-known pyralspite garnet group. Chemical zoning patterns of the garnets in the metamorphic rocks (schists differ from those in the igneous rocks (pegmatite, showing different compositions from core to rim. Petrographic evidence such as: co

  13. Fission track dating and estimation of uranium in some garnets of Rajasthan (India)

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S; Virk, H S [Punjabi Univ., Patiala (India). Dept. of Physics

    1978-09-01

    The experimental procedure, involving the preparation, etching, thermal neutron irradiation and scanning of the garnet samples, is described. The calculated fission track ages and uranium concentration are tabulated.

  14. Characterisation of debris from laser and mechanical cutting of bone.

    Science.gov (United States)

    Rachmanis, Nikolaos; McGuinness, Garrett B; McGeough, Joseph A

    2014-07-01

    Laser cutting of bones has been proposed as a technology in orthopaedic surgery. In this short study, the laser-bone interaction was examined using a pulsed erbium-doped yttrium aluminium garnet laser and compared to a conventional cutting technique. Microscopic analysis revealed the nature of waste debris and showed higher proportions of finer particles for conventional sagittal sawing compared to laser cutting. © IMechE 2014.

  15. Effect of Er:YAG Laser and Sandblasting in Recycling of Ceramic Brackets.

    Science.gov (United States)

    Yassaei, Soghra; Aghili, Hossein; Hosseinzadeh Firouzabadi, Azadeh; Meshkani, Hamidreza

    2017-01-01

    Introduction: This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting. Methods: Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores. Results: The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent. Conclusion: According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice.

  16. BONDING ALUMINUM METALS

    Science.gov (United States)

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  17. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  18. Distribution of garnet grain sizes and morphologies across the Moine Supergroup, northern Scottish Caledonides

    Science.gov (United States)

    Ashley, Kyle T.; Thigpen, J. Ryan; Law, Richard D.

    2016-04-01

    Garnet is used in a wide range of geologic studies due to its important physical and chemical characteristics. While the mineral is useful for thermobarometry and geochronology constraints and can often be correlated to deformation and fabric development, difficulties remain in making meaningful interpretations of such data. In this study, we characterize garnet grain sizes and crystal morphologies from 141 garnet-bearing metasedimentary rock samples collected from the northern part of the Moine Supergroup in the Scottish Caledonides. Larger, euhedral crystals are indicative of prograde metamorphic growth and are typically associated with the most recent phase of orogenesis (Scandian, ˜430 Ma). Small, rounded ("pin-head") garnets are interpreted as detrital in origin. A subhedral classification is more subjective and is used when garnets contains portions of straight boundaries but have rounded edges or rims that have been altered through retrograde metamorphic reactions. From our collection, 88 samples contain anhedral garnets (maximum measured grain size d = 0.46 ± 0.21 mm), 34 bear subhedral garnets (d = 2.0 ± 1.0 mm), and the remaining 19 samples contain garnets with euhedral grains (d = 4.4 ± 2.6 mm). Plotting the distribution of garnets relative to the mapped thrust contacts reveals an abrupt change in morphology and grain size when traced from the Moine thrust sheet across the Ben Hope and Sgurr Beag thrusts into the higher-grade, more hinterland-positioned thrust sheets. The dominance of anhedral garnets in the Moine thrust sheet suggests that these grains should not be used for peak P - T estimation associated with relatively low temperature (advance of interpreting large suits of garnet-derived thermodynamic and geochronologic data.

  19. Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study.

    Science.gov (United States)

    Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

    2017-11-01

    Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18  J/cm2 in the mesentery model and from 36 to 31  J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  20. Tactile Sensing From Laser-Ablated Metallized PET Films

    KAUST Repository

    Nag, Anindya; Mukhopadhyay, Subhas Chandra; Kosel, Jü rgen

    2016-01-01

    This paper reports the design, fabrication, and implementation of a novel sensor patch developed from commercial polyethylene terephthalate films metallized with aluminum on one side. The aluminum was ablated with laser to form interdigitated

  1. A comparative study of laser induced breakdown spectroscopy analysis for element concentrations in aluminum alloy using artificial neural networks and calibration methods

    International Nuclear Information System (INIS)

    Inakollu, Prasanthi; Philip, Thomas; Rai, Awadhesh K.; Yueh Fangyu; Singh, Jagdish P.

    2009-01-01

    A comparative study of analysis methods (traditional calibration method and artificial neural networks (ANN) prediction method) for laser induced breakdown spectroscopy (LIBS) data of different Al alloy samples was performed. In the calibration method, the intensity of the analyte lines obtained from different samples are plotted against their concentration to form calibration curves for different elements from which the concentrations of unknown elements were deduced by comparing its LIBS signal with the calibration curves. Using ANN, an artificial neural network model is trained with a set of input data of known composition samples. The trained neural network is then used to predict the elemental concentration from the test spectra. The present results reveal that artificial neural networks are capable of predicting values better than traditional method in most cases

  2. Curie temperature, exchange integrals, and magneto-optical properties in off-stoichiometric bismuth iron garnet epitaxial films

    Science.gov (United States)

    Vertruyen, B.; Cloots, R.; Abell, J. S.; Jackson, T. J.; da Silva, R. C.; Popova, E.; Keller, N.

    2008-09-01

    We have studied the influence of the stoichiometry on the structural, magnetic, and magneto-optical properties of bismuth iron garnet (Bi3Fe5O12) thin films grown by pulsed laser deposition. Films with different stoichiometries have been obtained by varying the Bi/Fe ratio of the target and the oxygen pressure during deposition. Stoichiometry variations influence the Curie temperature TC by tuning the (Fe)-O-[Fe] geometry: TC increases when the lattice parameter decreases, contrary to what happens in the case of stoichiometric rare-earth iron garnets. The thermal variation of the magnetization, the Faraday rotation, and the Faraday ellipticity have been analyzed in the frame of the Néel two-sublattice magnetization model giving energies of -48K (4.1 meV), -29K (2.5 meV), and 84 K (7.3 meV) for the three magnetic exchange integrals jaa , jdd , and jad , respectively. Magneto-optical spectroscopy linked to compositional analysis by Rutherford backscattering spectroscopy shows that Bi and/or Fe deficiencies also affect the spectral variation (between 1.77 and 3.1 eV). Our results suggest that bismuth deficiency has an effect on the magneto-optical response of the tetrahedral Fe sublattice, whereas small iron deficiencies affect predominantly the magneto-optical response of the octahedral sublattice.

  3. Remotely Exploring Deeper-Into-Matter by Non-Contact Detection of Audible Transients Excited by Laser Radiation

    Directory of Open Access Journals (Sweden)

    Javier Moros

    2017-12-01

    Full Text Available An acoustic spectroscopic approach to detect contents within different packaging, with substantially wider applicability than other currently available subsurface spectroscopies, is presented. A frequency-doubled Nd:YAG (neodymium-doped yttrium aluminum garnet pulsed laser (13 ns pulse length operated at 1 Hz was used to generate the sound field of a two-component system at a distance of 50 cm. The acoustic emission was captured using a unidirectional microphone and analyzed in the frequency domain. The focused laser pulse hitting the system, with intensity above that necessary to ablate the irradiated surface, transferred an impulsive force which led the structure to vibrate. Acoustic airborne transients were directly radiated by the vibrating elastic structure of the outer component that excited the surrounding air in contact with. However, under boundary conditions, sound field is modulated by the inner component that modified the dynamical integrity of the system. Thus, the resulting frequency spectra are useful indicators of the concealed content that influences the contributions originating from the wall of the container. High-quality acoustic spectra could be recorded from a gas (air, liquid (water, and solid (sand placed inside opaque chemical-resistant polypropylene and stainless steel sample containers. Discussion about effects of laser excitation energy and sampling position on the acoustic emission events is reported. Acoustic spectroscopy may complement the other subsurface alternative spectroscopies, severely limited by their inherent optical requirements for numerous detection scenarios.

  4. Laser soldering of Sn-Ag-Cu and Sn-Zn-Bi lead-free solder pastes

    Science.gov (United States)

    Takahashi, Junichi; Nakahara, Sumio; Hisada, Shigeyoshi; Fujita, Takeyoshi

    2004-10-01

    It has reported that a waste of an electronics substrate including lead and its compound such as 63Sn-37Pb has polluted the environment with acid rain. For that environment problem the development of lead-free solder alloys has been promoted in order to find out the substitute for Sn-Pb solders in the United States, Europe, and Japan. In a present electronics industry, typical alloys have narrowed down to Sn-Ag-Cu and Sn-Zn lead-free solder. In this study, solderability of Pb-free solder that are Sn-Ag-Cu and Sn-Zn-Bi alloy was studied on soldering using YAG (yttrium aluminum garnet) laser and diode laser. Experiments were peformed in order to determine the range of soldering parameters for obtaining an appropriate wettability based on a visual inspection. Joining strength of surface mounting chip components soldered on PCB (printed circuit board) was tested on application thickness of solder paste (0.2, 0.3, and 0.4 mm). In addition, joining strength characteristics of eutectic Sn-Pb alloy and under different power density were examined. As a result, solderability of Sn-Ag-Cu (Pb-free) solder paste are equivalent to that of coventional Sn-Pb solder paste, and are superior to that of Sn-Zn-Bi solder paste in the laser soldering method.

  5. Garnet Yield Strength at High Pressures and Implications for Upper Mantle and Transition Zone Rheology

    International Nuclear Information System (INIS)

    Kavner, A.

    2008-01-01

    Garnet helps control the mechanical behavior of the Earth's crust, mantle, and transition zone. Here, measurements are presented suggesting that garnet, long considered to be a high-viscosity phase, is actually weaker than the other dominant components in the transition zone. The mechanical behavior of garnet at high pressures was examined using radial diffraction techniques in the diamond anvil cell. The yield strength of grossular garnet was inferred from synchrotron X-ray measurements of differential lattice strains. The differential stress was found to increase from 1.3 (±0.6) GPa at a hydrostatic pressure 5.8 (±1.1) GPa to 4.1 (±0.4) GPa at 15.7 (±1.0) GPa, where it was level to 19 GPa. The strength results are consistent with inferred strength values for majorite garnet from measurements in the diamond cell normal geometry, bolstering the idea that garnet-structured materials may all have similar strengths. In this low-temperature, high differential stress regime, garnet is shown to be significantly weaker than anhydrous ringwoodite and to have a strength similar to hydrous ringwoodite. This result suggests that the presence of water in the transition zone may not be required to explain a weak rheology, and therefore models of transition zone behavior built assuming that garnet is the high-strength phase may need to be revised.

  6. Ce3+-Doped garnet phosphors : Composition modification, luminescence properties and applications

    NARCIS (Netherlands)

    Xia, Zhiguo; Meijerink, Andries

    2017-01-01

    Garnets have the general formula of A3B2C3O12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce3+-doped garnet phosphors have a long

  7. Tibetan garnet records early Eocene initiation of thickening in the Himalaya

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Hacker, Bradley; Lee, Jeffrey

    2014-01-01

    Tectonic reconstructions of the Himalayan orogeny depend on the age at which crustal thickening commenced. To investigate this age, we analyzed garnet from middle crustal rocks exposed in the north Himalayan Mabja and Kangmar gneiss domes of Tibet using Lu-Hf geochronology. Garnet yielded Lu-Hf a...

  8. Topical eflornithine hydrochloride improves the effectiveness of standard laser hair removal for treating pseudofolliculitis barbae: a randomized, double-blinded, placebo-controlled trial.

    Science.gov (United States)

    Xia, Yang; Cho, Sunghun; Howard, Robin S; Maggio, Kurt L

    2012-10-01

    Pseudofolliculitis barbae (PFB) significantly impacts the military population, especially deployed personnel. This study was designed to determine whether the addition of topical eflornithine to hair laser treatment would improve efficacy in treating PFB. This was a randomized, double-blinded, placebo-controlled, paired (right and left neck) comparison study examining a combination of eflornithine and hair laser versus placebo and hair laser for the treatment of PFB. In all, 27 male patients with clinical PFB were treated with a long-pulsed neodymium:yttrium-aluminum-garnet laser with an energy fluence of 25 to 30 J/cm(2), a pulse duration of 20 to 30 milliseconds, and a 10-mm spot size to the entire bearded neck region. The laser treatment was performed every 4 weeks for a total of 16 weeks. Between laser treatments, patients applied eflornithine and placebo creams twice daily to opposite sides of the bearded neck region. The number of hairs and inflammatory papules were counted bilaterally at each visit. The eflornithine side had a statistically significant decrease in the number of hairs and inflammatory papules compared with the placebo side. At 16 weeks, the eflornithine side had a median hair reduction of 99.5% from baseline (range 48.5%-100.0%), whereas the placebo side had an 85.0% median hair reduction from baseline (range 50.5%-94.5%), P less than .001. Patients were not followed up beyond 16 weeks. The addition of topical eflornithine to hair laser treatment decreased hairs and inflammatory papules faster when compared with hair laser therapy alone in the treatment of PFB. Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  9. Anodizing Aluminum with Frills.

    Science.gov (United States)

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  10. Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer

    Science.gov (United States)

    Thomas, Jay B.; Spear, Frank S.

    2018-05-01

    Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston-cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm-1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P-T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from - 0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P-T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than 10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.

  11. Is the Aluminum Hypothesis Dead?

    Science.gov (United States)

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  12. Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

    Directory of Open Access Journals (Sweden)

    Mohammad Nur-E-Alam

    2015-04-01

    Full Text Available The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

  13. Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

    Science.gov (United States)

    Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

    2015-01-01

    The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

  14. The aluminum smelting process.

    Science.gov (United States)

    Kvande, Halvor

    2014-05-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development.

  15. Influence of scan strategy and molten pool configuration on microstructures and tensile properties of selective laser melting additive manufactured aluminum based parts

    Science.gov (United States)

    Dai, Donghua; Gu, Dongdong; Zhang, Han; Xiong, Jiapeng; Ma, Chenglong; Hong, Chen; Poprawe, Reinhart

    2018-02-01

    Selective laser melting additive manufacturing of the AlSi12 material parts through the re-melting of the previously solidified layer using the continuous two layers 90° rotate scan strategy was conducted. The influence of the re-melting behavior and scan strategy on the formation of the ;track-track; and ;layer-layer; molten pool boundaries (MPBs), dimensional accuracy, microstructure feature, tensile properties, microscopic sliding behavior and the fracture mechanism as loaded a tensile force has been studied. It showed that the defects, such as the part distortion, delamination and cracks, were significantly eliminated with the deformation rate less than 1%. The microstructure of a homogeneous distribution of the Si phase, no apparent grain orientation on both sides of the MPBs, was produced in the as-fabricated part, promoting the efficient transition of the load stress. Cracks preferentially initiate at the ;track-track; MPBs when the tensile stress increases to a certain value, resulting in the formation of the cleavage steps along the tensile loading direction. The cracks propagate along the ;layer-layer; MPBs, generating the fine dimples. The mechanical behavior of the SLM-processed AlSi12 parts can be significantly enhanced with the ultimate tensile strength, yield strength and elongation of 476.3 MPa, 315.5 MPa and 6.7%, respectively.

  16. Formation of atoll garnets in the UHP eclogites of the Tso Morari Complex, Ladakh, Himalaya

    Science.gov (United States)

    Jonnalagadda, Mallika K.; Karmalkar, Nitin R.; Duraiswami, Raymond A.; Harshe, Shivani; Gain, Sarah; Griffin, William L.

    2017-12-01

    The eclogites of the Tso Morari Complex, Ladakh, NW Himalayas preserve both garnets with spectacular atoll textures, as well as whole porphyroblastic garnets. Whole garnets are euhedral, idiomorphic and enclose inclusions of amphibole, phengite and zoisite within the cores, and omphacite and quartz/coesite towards the rims. Detailed electron microprobe analyses and back-scattered electron images show well-preserved prograde zoning in the whole garnets with an increase in Mg and decrease in Ca and Mn contents from the core to the rim. The atoll garnets commonly consist of euhedral ring over island/peninsular core containing inclusions of phengite, omphacite and rarely amphibole between the core and ring. Compositional profiles across the studied atoll grains show elemental variations with higher concentrations of Ca and Mn with low Mg at the peninsula/island cores; contrary to this low Ca, Mn and high Mg is observed at the outer rings. Temperature estimates yield higher values at the Mg-rich atoll garnet outer rings compared to the atoll cores. Atoll garnet formation was favoured by infiltration of fluid formed due to breakdown of hydrous phases, and/or the release of structurally bounded OH from nominally anhydrous minerals at the onset of exhumation. Infiltration of fluids along pre-existing fracture pathways and along mineral inclusion boundaries triggered breakdown of the original garnet cores and released elements which were subsequently incorporated into the newly-grown garnet rings. This breakdown of garnet cores and inward re-growth at the outer ring produced the atoll structure. Calibrated geo-thermobarometers and mineral equilibria reflect that the Tso Morari eclogites attain peak pressures prior to peak temperatures representing a clockwise path of evolution.

  17. Effects of neodymium concentration on optical characteristics of polycrystalline Nd:YAG laser materials

    International Nuclear Information System (INIS)

    Ikesue, A.; Kamata, K.; Yoshida, K.

    1996-01-01

    A neodymium-doped yttrium-aluminum garnet (Y 3 Al 5 O 12 , YAG) (Nd:YAG) ceramic that contained 0.3--4.8 at.% neodymium additives and exhibited nearly the same optical properties as those of a single crystal was fabricated by a solid-state reaction method using high-purity powders. Although the integrated absorption intensity of the 2 H 9/2 + 4 F 5/2 bands simply increased as the neodymium concentration in the YAG ceramics decreased, the fluorescence intensity of the 2.4 at.% Nd:YAG ceramic was the strongest among Nd:YAG ceramics with various neodymium concentrations and a 0.9 at.% Nd:YAG single crystal. An oscillation experiment was performed on a continuous-wave (cw) laser with a diode-laser exciting system using those ceramics and the single crystal. The oscillation threshold and slope efficiency in that analysis were 309 mW and 28%, respectively, for the 1.1 at.% Nd:YAG ceramics and 356 mW and 40%, respectively, for the 2.4 at.% Nd:YAG ceramics. The lasing characteristics of the ceramics in the present work were superior to those of a 0.9 at.% Nd:YAG single crystal that was fabricated by the Czochralski (Cz) method

  18. Angular distribution of atoms ejected by laser ablation of different metals

    International Nuclear Information System (INIS)

    Konomi, I.; Motohiro, T.; Asaoka, T.

    2009-01-01

    Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm 2 ) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos n θ distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

  19. Effects of Root Debridement With Hand Curettes and Er:YAG Laser on Chemical Properties and Ultrastructure of Periodontally-Diseased Root Surfaces Using Spectroscopy and Scanning Electron Microscopy

    Science.gov (United States)

    Amid, Reza; Gholami, Gholam Ali; Mojahedi, Masoud; Aghalou, Maryam; Gholami, Mohsen; Mirakhori, Mahdieh

    2017-01-01

    Introduction: The efficacy of erbium-doped yttrium aluminum garnet (Er:YAG) laser for root debridement in comparison with curettes has been the subject of many recent investigations. Considering the possibility of chemical and ultra-structural changes in root surfaces following laser irradiation, this study sought to assess the effects of scaling and root planing (SRP) with curettes and Er:YAG laser on chemical properties and ultrastructure of root surfaces using spectroscopy and scanning electron microscopy (SEM). Methods: In this in vitro experimental study, extracted sound human single-rooted teeth (n = 50) were randomly scaled using manual curettes alone or in conjunction with Er:YAG laser at 100 and 150 mJ/pulse output energies. The weight percentages of carbon, oxygen, phosphorous and calcium remaining on the root surfaces were calculated using spectroscopy and the surface morphology of specimens was assessed under SEM. Data were analyzed using one-way analysis of variance (ANOVA). Results: No significant differences (P > 0.05) were noted in the mean carbon, oxygen, phosphorous and calcium weight percentages on root surfaces following SRP using manual curettes with and without laser irradiation at both output energies. Laser irradiation after SRP with curettes yielded rougher surfaces compared to the use of curettes alone. Conclusion: Although laser irradiation yielded rougher surfaces, root surfaces were not significantly different in terms of chemical composition following SRP using manual curettes with and without Er:YAG laser irradiation. Er:YAG laser can be safely used as an adjunct to curettes for SRP. PMID:28652898

  20. Correlation of Weld Appearance with Microstructure and Mechanical Properties of 2024-T4 Aluminum Alloy Welded by Fiber Laser with Filler Wire

    Directory of Open Access Journals (Sweden)

    XU Fei

    2017-11-01

    Full Text Available Two typical cross-section of welds, including nail shape and near X shape, are obtained in the process of fiber laser welding 2024-T4 Al alloy with filler wire. The correlations of the two weld appearances and other elements (such as microstructure, microhardness, and joint's tensile properties were analyzed. The results show that the weld with near X shape cross-section during the welding process is more stable than that with nail shape cross-section, and the welding spatter of the former is smaller than that of the latter. The microstructure of the weld zone is columnar grains and equiaxed grains, the columnar grains are formed near the fusion line and growing along the vertical direction of the fusion line, the equiaxed grains are distributed in the center of the weld zone. The secondary dendrite of the grains in the center of the weld with nail shape cross-section grows better, and gradually forms to equiaxed dendrite, while the grains size of the weld with near X shape cross-section is relatively finer, exhibiting equiaxed cellular grain. Compared with the joint with nail shape cross-section of the weld, the joint with near X shape cross-section of the weld have some different characteristics, the precipitation strengthening phase θ(Al2Cu content in weld zone of the latter is more than that of the former, the average microhardness value of the weld zone of the latter is higher than that of the former, the softening phenomenon of heat affect zone (HAZ of the latter is weaker than that of the former, and the joint's tensile strength and plasticity of the latter are lower than that of the former slightly.

  1. Studies of the mechanisms involved in the laser surface hardening process of aluminum base alloys; Estudos dos mecanismos envolvidos em processos de endurecimento superficial a laser de ligas a base de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Luciana Ventavele da

    2011-07-01

    The Al-Si alloys are widely used in industry to replace the steel and gray cast iron in high-tech sectors. The commercial importance of these alloys is mainly due to its low weight, excellent wear (abrasion) and corrosion resistance, high resistance at elevated temperatures, low coefficient of thermal expansion and lesser fuel consumption that provide considerable reduction of emission of pollutants. In this work, Al-Si alloy used in the automotive industry to manufacture pistons of internal combustion engines, was undergone to surface treatments using LASER remelting (Nd:YAG, {lambda} = 1.06 {mu}m, pulsed mode). The LASER enables various energy concentrations with accurate transfer to the material without physical contact. The intense energy transfer causes the occurrence of structural changes in the superficial layer of the material. Experiments with single pulses and trails were conducted under various conditions of LASER processing in order to analyze microstructural changes resulting from treatments and their effects on the hardness. For the characterization of hardened layer was utilized the following techniques: optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray mapping, Vickers microhardness and maximum roughness tests. The high cooling rate caused a change in the alloy structure due to the refinement of the primary eutectic silicon particles, resulting in increase of the mechanical properties (hardness) of the Al-Si alloy. (author)

  2. YAG laser peripheral iridotomy for the prevention of pigment dispersion glaucoma a prospective, randomized, controlled trial.

    Science.gov (United States)

    Scott, Andrew; Kotecha, Aachal; Bunce, Catey; Balidis, Miltos; Garway-Heath, David F; Miller, Michael H; Wormald, Richard

    2011-03-01

    To test the hypothesis that neodymium:yttrium-aluminum-garnet (Nd:YAG) laser peripheral iridotomy (LPI) significantly reduces the incidence of conversion from pigment dispersion syndrome (PDS) with ocular hypertension (OHT) to pigmentary glaucoma (PG). Prospective, randomized, controlled 3-year trial. One hundred sixteen eyes of 116 patients with PDS and OHT. Patients were assigned randomly either to Nd:YAG LPI or to a control group (no laser). The primary outcome measure was conversion to PG within 3 years, based on full-threshold visual field (VF) analysis using the Ocular Hypertension Treatment Study criteria. Secondary outcome measures were whether eyes required topical antiglaucoma medications during the study period and the time to conversion or medication. Fifty-seven patients were randomized to undergo laser treatment and 59 were randomized to no laser (controls). Age, gender, spherical equivalent refraction, and intraocular pressure at baseline were similar between groups. Outcome data were available for 105 (90%) of recruited subjects, 52 in the laser treatment group and 53 in the no laser treatment group. Patients were followed up for a median of 35.9 months (range, 10-36 months) in the laser arm and 35.9 months (range, 1-36 months) in the control arm. Eight eyes (15%) in the laser group and 3 eyes (6%) in the control group converted to glaucoma in the study period. The proportion of eyes started on medical treatment was similar in the 2 groups: 8 eyes (15%) in the laser group and 9 eyes (17%) in the control group. Survival analyses showed no evidence of any difference in time to VF progression or commencement of topical therapy between the 2 groups. Cataract extraction was performed on 1 patient in the laser group and in 1 patient in the control group during the study period (laser eye at 18 months; control eye at 34 months). This study suggests that there was no benefit of Nd:YAG LPI in preventing progression from PDS with OHT to PG within 3 years of

  3. Determination of the position of the 5d excited levels of Ce.sup.3+./sup. ions with respect to the conduction band in the epitaxial films of the multicomponent (Lu,Gd).sub.3./sub.(Ga,Al).sub.5./sub.O.sub.12./sub.:Ce garnets

    Czech Academy of Sciences Publication Activity Database

    Babin, Vladimir; Hanuš, M.; Krasnikov, A.; Kučera, M.; Nikl, Martin; Zazubovich, S.

    2016-01-01

    Roč. 62, Dec (2016), s. 465-474 ISSN 0925-3467 R&D Projects: GA ČR GA16-15569S Institutional support: RVO:68378271 Keywords : luminescence * multicomponent garnets * epitaxial films * scintillators Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.238, year: 2016

  4. Preparing magnetic yttrium iron garnet nanodot arrays by ultrathin anodic alumina template on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Hui; Han, Mangui, E-mail: han-mangui@yahoo.com; Deng, Longjiang [National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zheng, Liang; Zheng, Peng; Qin, Huibin [Institute of Electron Device and Application, Hangzhou Dianzi University, Hangzhou 310008 (China); Wu, Qiong [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

    2015-08-10

    Ultrahigh density periodically ordered magnetic yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) nanodot arrays have been prepared by pulsed laser deposition through an ultrathin alumina mask (UTAM). UTAM having periodically ordered circularly shaped holes with 350 nm in diameter, 450 nm in inter-pore distance, and 700 nm in height has been prepared on silicon substrate. Furthermore, the microstructure and magnetic properties of YIG nanodot arrays have been characterized. Nanodot arrays with a sharp distribution in diameter centered at 340 nm with standard deviation of 10 nm have been fabricated. Moreover, typical hysteresis loops and ferromagnetic resonance spectra in in-plane and out-of-plane revealed that this unique structure greatly influences the magnetics properties of YIG. First, coercivity of YIG nanodot arrays in in-plane was increased about from 15 Oe of YIG films to 500 Oe. Then, the degree of uniformity about nanodot height decided that two or more resonance peaks in out-of-plane were detected in the spectra. The peak-to-peak linewidth values were about 94 Oe and 40 Oe in the parallel and perpendicular directions, respectively, which indicated that the values were larger by the two-magnon scattering. Consequently, this pattering method creates opportunities for studying physics in oxide nanomagnets and may be applied in spin-wave devices.

  5. Treatment of Laugier-Hunziker syndrome with the Q-switched alexandrite laser in 22 Chinese patients.

    Science.gov (United States)

    Zuo, Ya-Gang; Ma, Dong-Lai; Jin, Hong-Zhong; Liu, Yue-Hua; Wang, Hong-Wei; Sun, Qiu-Ning

    2010-03-01

    Laugier-Hunziker syndrome (LHS), a rare, acquired pigmentary disorder of the lips, oral mucosa, and fingers, is known to be an entirely benign disease with no systemic manifestations. In the past, the pigmentation has been treated efficiently in a few patients with the Q-switched neodymium: yttrium-aluminum-garnet (Nd:YAG) laser and the Q-switched alexandrite laser (QSAL). In order to evaluate the efficacy and safety of QSAL on Chinese patients of LHS, we treated 22 patients with QSAL in the past 5 years. Treatments were delivered on a bimonthly or trimonthly basis until the abnormal pigmentation totally disappeared. Patients were evaluated at each visit for evidence of dyspigmentation, scarring, or other untoward effects from the laser treatment. Our 22 subjects consisted of 18 females and 4 males with a mean age of 42.4 years. After only one session of laser treatment, the clearing on the lips was as follow: 18 (81.8%) excellent, 2 (9.1%) good, 1 (4.5%) fair and 1 (4.5%) poor. Eighteen patients (81.8%) with LHS, who had achieved excellent clearing after only one session of laser treatment, did not receive further treatment. Among the left four patients, three patients (13.6%) achieved complete results after three laser treatments. Only one patient required six sessions to achieve complete clearance. No scarring was noted after any of the treatments. The appearance of pigmentation on mucous membranes in a middle-aged patient without a significant family history for skin disorders should prompt consideration for the possible diagnosis of LHS. Our study has also demonstrated QSAL to be highly effective and safe in the treatment of LHS.

  6. Study of nanodispersed aluminum and iron alcosols by photoacoustic spectroscopy

    Science.gov (United States)

    An, Vladimir; de Izarra, Charles; Saveliev, Gennady

    2011-06-01

    Nanodispersed aluminum and iron alcosols were prepared by ultrasonic dispersion of nanodispersed aluminum and iron powders in absolute ethanol. The photoacoustic signal (PAS) produced in modulated CO2 laser irradiation (1.026 and 1.096 kHz) of alcosols depends on the nature and method of nanoparticle fabrication and does not depend on their concentration in ethanol (within 1-5 g/l). Chemical interaction between metal nanoparticles and ethanol activated by laser irradiation or/and ultrasound is considered as the cause of the PAS.

  7. A Study of Defect Behavior in Almandine Garnet

    Science.gov (United States)

    Geiger, C. A.; Brearley, A. J.; Dachs, E.; Tipplet, G.; Rossman, G. R.

    2016-12-01

    Transport and diffusion in crystals are controlled by defects. However, a good understanding of the defect types in many silicates, including garnet, is not at hand. We undertook a study on synthetic almandine, ideal end-member Fe3Al2Si3O12, to better understand its precise chemical and physical properties and defect behavior. Crystals were synthesized at high pressures and temperatures under different fO2 conditions using various starting materials with H2O and without. The almandine obtained came in polycrystalline and single-crystal form. The synthetic reaction products and crystals were carefully characterized using X-ray powder diffraction, electron microprobe and TEM analysis and with 57Fe Mössbauer, UV/VIS single-crystal absorption and IR single-crystal spectroscopy. Various possible intrinsic defects, such as the Frenkel, Schottky and site-disorder types, along with Fe3+, in both synthetic and natural almandine crystals, were analyzed based on model defects expressed in Kröger-Vink notation. Certain types of minor microscopic- to macroscopic-sized precipitation or exsolution phases, including some that are nanosized, that are observed in synthetic almandine (e.g., magnetite), as well as in more compositionally complex natural crystals (e.g., magnetite, rutile, ilmenite), may result from defect reactions. An explanation for their origin through minor amounts of defects in garnet has certain advantages over other models that have been put forth in the literature that assume strict garnet stoichiometry for their formation and/or open-system atomic transport over relatively long length scales. Physical properties, including magnetic, electrical conductivity and diffusion behavior, as well as the color, of almandine are also analyzed in terms of various possible model defects. It is difficult, if not impossible, to synthesize stoichiometric end-member almandine, Fe3Al2Si3O12, in the laboratory, as small amounts of extrinsic OH- and/or Fe3+ defects, for example

  8. Microstructures and physical properties of waste garnets as a promising construction materials

    Directory of Open Access Journals (Sweden)

    Habeeb Lateef Muttashar

    2018-06-01

    Full Text Available Rapid industrial growth has witnessed the ever-increasing utilization of sand from rivers for various construction purposes, which caused an over-exploitation of rivers’ beds and disturbed the eco-system. strong engineering properties of waste garnets offer a recycling alternative to create efficient construction materials. Recycling of garnets provides a cost-effective and environmentally responsible solution rather than dumping it as industrial waste. In this spirit, this article presents an investigation into the capacity of spent garnets as sand replacement. The main parameters studied were the evolution of leaching performance, microstructure of the raw spent garnet and sand specimens. The microstructures, boning vibrations and thermal properties of the raw materials were determined using X-ray diffraction (XRD, field emission scanning microscopy (FESEM, Fourier transform infrared (FTIR spectroscopy, and thermo gravimetric analysis (TGA. Admirable features of the results suggest that the spent garnet is proven to be suitable replacement of sand. It is established that proper exploitation of spent garnet as an alternative to sand could save the earth from depleting the natural resources which is essential for sustainable development. Keywords: Spent garnet, Sand, Micro-structures, Recycling, Concrete

  9. Study of the provenance of Belgian Merovingian garnets by PIXE at IPNAS cyclotron

    International Nuclear Information System (INIS)

    Mathis, F.; Vrielynck, O.; Laclavetine, K.; Chene, G.; Strivay, D.

    2008-01-01

    Recent archaeological excavation in Belgium reveals one of the biggest Merovingian necropolis ever found in this country. This necropolis contains 436 tombs with a period of occupation of almost two centuries. Some of these tombs were very rich, especially two of them, and delivered an important funerary furniture. About 60 jewels inlaid with red garnets have been found, most of them of 'cloisonne' style (namely about 450 garnets). The new extracted beam set-up of the IPNAS cyclotron (University of Liege, Belgium) has been improved in order to analyse by PIXE these garnets and try to determine their provenance. These analyses reveal that the garnets found in the necropolis of Grez-Doiceau are very homogeneous in composition (almandine garnets) and are coming almost from a unique source. These results have been compared to previous studies led in France during these past five years. This permits to identify the source of almandine garnet situated in India and to highlight differences in garnet supply between France and Belgium in Merovingian times

  10. Combined 595-nm and 1,064-nm laser irradiation of recalcitrant and hypertrophic port-wine stains in children and adults.

    Science.gov (United States)

    Alster, Tina S; Tanzi, Elizabeth L

    2009-06-01

    Although pulsed dye laser (PDL) treatment of port-wine stain (PWS) has long been proven safe and effective, incomplete clearance of these vascular malformations can be problematic. In addition, advanced PWS with deeper coloration and tissue hypertrophy can be particularly difficult to treat because of the superficial dermal penetration of 585- to 595-nm light. The purpose of this study was to evaluate the safety and efficacy of a novel device that delivers sequential pulses of 595- and 1,064-nm wavelengths in the treatment of recalcitrant and hypertrophic PWS. Twenty-five children and adults (skin phototypes I-III) with recalcitrant or hypertrophic PWS showing incomplete clearance after 10 prior PDL treatments were included in the study. Successive treatments using a 595-nm PDL and a 1,064-nm neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser were delivered at 6- to 8-week intervals. Two masked assessors determined clinical improvement of treatment areas using independent evaluation of comparative photographs at baseline and 3 months after treatment using a standard quartile grading scale. The use of dual 595-/1,064-nm wavelengths provided continued improvement of PWS that were previously recalcitrant to ongoing PDL therapy. Side effects were limited to transient erythema, edema, and mild purpura. Rare vesicle formation was observed, with no subsequent scarring or undesirable pigmentary changes. The novel dual 595-nm PDL and 1,064-nm Nd:YAG laser is an effective treatment for PWS that are recalcitrant to PDL therapy alone.

  11. Advances in aluminum anodizing

    Science.gov (United States)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  12. Corrosion Inhibitors for Aluminum.

    Science.gov (United States)

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  13. Corrosion Protection of Aluminum

    Science.gov (United States)

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  14. Tunable negative index metamaterial using yttrium iron garnet

    International Nuclear Information System (INIS)

    He, Yongxue; He, Peng; Dae Yoon, Soack; Parimi, P.V.; Rachford, F.J.; Harris, V.G.; Vittoria, C.

    2007-01-01

    A magnetic field tunable, broadband, low-loss, negative refractive index metamaterial is fabricated using yttrium iron garnet (YIG) and a periodic array of copper wires. The tunability is demonstrated from 18 to 23 GHz under an applied magnetic field with a figure of merit of 4.2 GHz/kOe. The tuning bandwidth is measured to be 5 GHz compared to 0.9 GHz for fixed field. We measure a minimum insertion loss of 4 dB (or 5.7 dB/cm) at 22.3 GHz. The measured negative refractive index bandwidth is 0.9 GHz compared to 0.5 GHz calculated by the transfer function matrix theory and 1 GHz calculated by finite element simulation

  15. Thermal conductivity of yttrium iron garnet at low temperatures

    International Nuclear Information System (INIS)

    Joshi, Y.P.; Sing, D.P.

    1979-01-01

    An analysis of the low-temperature thermal conductivity of yttrium iron garnet is presented giving consideration to the fact that in a conventional conductivity experiment the magnon temperature gradient inside a magnetic insulator need not be necessarily equal to the phonon temperature gradient. Consequently the effective conductivity can be less than the algebraic sum of the phonon and magnon intrinsic conductivities, depending on the magnon-phonon thermal relaxation rate. This relaxation rate has been distinguished from the individual phonon and magnon relaxation rates and an expression is derived for it. Theoretical calculations of the effective conductivity are found to be in good agreement with experimental results. The contribution of magnons to the effective conductivity is observed to be small at all temperatures below the conductivity maximum. (author)

  16. Study of Y and Lu iron garnets using Bethe-Peierls-Weiss method

    Science.gov (United States)

    Goveas, Neena; Mukhopadhyay, G.; Mukhopadhyay, P.

    1994-11-01

    We study here the magnetic properties of Y- and Lu- Iron Garnets using the Bethe- Peierls-Weiss method modified to suit complex systems like these Garnets. We consider these Garnets as described by Heisenberg Hamiltonian with two sublattices (a,d) and determine the exchange interaction parameters Jad, Jaa and Jdd by matching the exerimental susceptibility curves. We find Jaa and Jdd to be much smaller than those determined by Néel theory, and consistent with those obtained by the study of spin wave spectra; the spin wave dispersion relation constant obtained using these parameters gives good agreement with the experimental values.

  17. Optical spectroscopy of the Ce-doped multicomponent garnets

    International Nuclear Information System (INIS)

    Canimoglu, A.; Karabulut, Y.; Ayvacikli, M.; Muresan, L.E.; Perhaita, I.; Barbu-Tudoran, L.; Garcia Guinea, J.; Karali, T.; Can, N.

    2016-01-01

    Here, we report our results referring to the preparation of Ce doped Y 2.22 MgGa 2 Al 2 SiO 12 , Y 1.93 MgAl 4 SiO 12 and Y 2.22 Gd 0.75 Ga 2 Al 3 O 12 using solid state reaction at high temperature. Several complementary methods (i.e. powder x-ray diffraction (XRPD), energy dispersive analysis of X-rays (EDX), scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR)) were studied to examine the effects of the synthesis procedure on the morphology and structure. XRD analyses revealed that all compounds include yttrium aluminate phase with garnet structure. Cathodoluminescence (CL), radioluminescence (RL) and photoluminescence (PL) measurements were carried out for clarification of relationship between host lattice defects and the spectral luminescence emissions. Luminescence emission of phosphors is peaked at 530 nm assigned to 5d-4f transitions of the dopant Ce 3+ ions with a broad emission band in 400–700 nm range. Under electron irradiation, the emission spectrum of Ce doped (YGd) 3 Ga 2 Al 3 O 12 is well defined and has a characteristic fairly narrow and sharp emission band peaking at 312 nm and 624 nm corresponding to transition of 6 P 7/2 → 8 S 7/2 and 6 G J → 6 P J (Gd 3+ ), respectively. We suggest some of phosphors might be excellent phototherapy phosphor materials under electron excitation. - Highlights: • Ce-doped Multicomponent Garnets were prepared solid state reaction method. • The shape and size of phosphor particles were examined. • The narrow band UV B emission due to Gd 3+ ions were observed.

  18. Nanoscale aluminum concaves for light-trapping in organic thin-films

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jaroslaw; Adam, Jost; Cielecki, Pawel Piotr

    2016-01-01

    Anodic aluminum oxide (AAO) templates, fabricated from oxalic acid and phosphoric acid, lead to non-periodic nanoscale concave structures in their underlying aluminum layer, which are investigated for their field-enhancement properties by applying a thin-film polymer coating based laser ablation...

  19. High efficiency laser action in mildly doped Yb:LuYAG ceramics

    Czech Academy of Sciences Publication Activity Database

    Pirri, A.; Toci, G.; Li, J.; Xie, T.; Pan, Y.; Babin, Vladimir; Beitlerová, Alena; Nikl, Martin; Vannini, M.

    2017-01-01

    Roč. 73, Nov (2017), s. 312-318 ISSN 0925-3467 Institutional support: RVO:68378271 Keywords : laser ceramic s * Yb laser * mixed garnets * LuYAG Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.238, year: 2016

  20. Apraclonidine versus brinzolamide-timolol combination to prevent intraocular pressure elevation after laser capsulotomy

    Di